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timer Asked: Apr 13th, 2020

Question Description

Please include (and number) the following in your project:

*complete from the orgo file uploaded.

1. Provide the title of your article

Copy/Paste the URL of the page showing the FULL-TEXT article that you have found into your submission!

Write A) page number of your reaction in the article, B) the Scheme, Figure, or Table that your reaction is shown in, C) the bold compound number of your product, and D) the page that your compound's experimental procedure/characterization information are shown in the supporting information.

2. Summarize the article and state the importance of the project briefly. This counts towards the 400-600 word project total.

3. Draw the chiral molecule product from your reaction and label at least one of its chiral centers (R/S). Draw the enantiomer of your chiral molecule and label the corresponding chiral center R/S. DO NOT CUT/PASTE FROM THE ARTICLE – DRAW IT IN PEN, PENCIL, OR CHEMDRAW.

4. Draw the FULL, ARROW-PUSHING MECHANISM for your reaction of choice. DO NOT CUT/PASTE FROM THE ARTICLE – DRAW IT IN PEN, PENCIL, OR CHEMDRAW. (It can be handy to draw the mechanism down the page and verbalize the mechanism step-by-step adjacent to it.)

5. Give a verbalization of the mechanism you are going to show from the article. Do not plagiarize from the internet. Use your own words. This counts towards the 400-600 word project total.

6. Detail the spectroscopy for the product of your reaction. Show the proton and carbon NMR and label ALL the product's H to show that you know what H-NMR peaks correspond to each hydrogen atoms on your molecule. On another drawing of your molecule, label the carbons and correspond them to the carbon peaks on the NMR.

You can use Chemdraw to help you figure out roughly where a peak should show up, but DO NOT use the ChemDraw peaks or predicted spectra as your project data!! Use the proton and carbon peaks given in the article/supporting information!!!!

7. Describe the chromatography method used to isolate the product. Include the solvent conditions needed to isolate your product, the amount of yield, and the percent yield. This counts towards the 400-600 word project total.

8. Cite the article using the following format that is used by Angewandte Chemie. This was already done in the first step where you found your article, so this should be done unless you changed articles.

First Initial. Last Name, First Initial. Last Name, (list all authors) Journal Name in Italics (abbreviate as shown below), year, volume in bold, page range of article.

Example 1: P. Selig, T. Bach, Angew. Chem. 2008, 120, 51605162.

9. Save the article PDF and supporting information PDF. The TAs and I need to be able to read it to get full points. A file format other than PDF may hinder our ability to open your document and provide you points. These will be attached files added to the comments section for us to cross-reference.

10. Check Length - Use a minimum of 400 words and a maximum of 600 words. If your Turn-it-in score is a little high, try adding another sentence to the summary/importance section so that the highlighted portion is a smaller amount of the total words....or note the flagged sections and rewrite them in your own words.

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Angewandte Communications Natural Products Synthesis Chemie International Edition: DOI: 10.1002/anie.201611606 German Edition: DOI: 10.1002/ange.201611606 A 11-Steps Total Synthesis of Magellanine through a Gold(I)-Catalyzed Dehydro Diels–Alder Reaction Philippe McGee, GeneviHve B8tournay, Francis Barab8, and Louis Barriault* Abstract: We have developed an innovative strategy for the formation of angular carbocycles via a gold(I)-catalyzed dehydro Diels–Alder reaction. This transformation provides rapid access to a variety of complex angular cores in excellent diastereoselectivities and high yields. The usefulness of this AuI-catalyzed cycloaddition was further demonstrated by accomplishing a 11-steps total synthesis of (:)-magellanine. The development of new transformations for the efficient synthesis of architecturally complex scaffolds via operationally simple and practical protocols is of paramount importance.[1] In this regard, the specific affinity of cationic gold complexes for p-system and their ability to stabilize neighboring cationic charges have stimulated the development of efficient and reliable methods for the construction of C@C bonds.[2] The cycloaddition between an enyne and a olefin known as the dehydro Diels–Alder reaction (DDA) is a expedient process for the synthesis of cyclohexadienes and related carbocycles [Eq. (1)].[3] While the thermal DDA reaction is well documented, the use of transition metals to catalyze this reaction remains marginal.[4] In pioneering work, Echavarren and co-workers[5] reported a AuI-catalyzed cyclization of arylenyne/dienyne 1 to give substituted tetrahydronaphthalenes 3 through a stepwise process involving a cyclopropyl gold(I)–carbene intermediate 2 (Scheme 1) [Eq. (2)].[6] Recently, we[7] and others[8] reported that a divergent pathway for carbocyclization can be achieved by modulating the steric and electronic properties of the gold(I) catalyst. On that basis, we envisioned that a gold(I)-catalyzed intramolecular formal [4+ +2] cycloaddition between an enyne and an enol ether 4 would proceed regio- and stereoselectively to generate tricyclic angular core 6 through the organogold intermediate 5 [Eq. (3)].[9] These ubiquitous structural scaffolds are embedded in a broad variety of naturally occurring complex alkaloids and terpenes [*] P. McGee, G. B8tournay, F. Barab8, Prof. L. Barriault Center for Catalysis Research and Innovation, Department of Chemistry and Biomolecular Sciences, University of Ottawa 10 Marie-Curie, Ottawa, K1N 6N5 (Canada) E-mail: louis.barriault@uottawa.ca Supporting information and the ORCID identification number(s) for the author(s) of this article can be found under http://dx.doi.org/10. 1002/anie.201611606. 6280 Scheme 1. Gold-catalyzed dehydro Diels–Alder reaction. such as magellanine (7), dankasterone (8) and conidiogenol (9), to name a few. Herein, we report an efficient and stereoselective AuI-catalyzed DDA reaction that enables the preparation of angular carbocycles and its application to a short synthesis of (:)-magellanine (7). At the outset of our investigation, the enol 10 a was prepared and subjected to the AuI-catalyzed DDA using [L1AuNCMe]SbF6 (2.5 mol %) (Table 1). After screening various solvents, high yields were observed in toluene (entry 1). Although the carbocyclization gave a mixture of three products 11 a, 12 a and 13 a in a ratio of 6:6:1, we were pleased to observe only one diastereomer in each case. Further optimizations showed that reduction of the catalyst loading to 1 mol % did not affect the reaction outcome (entry 2). However, lower reaction yields were noticed with loadings below 1 mol % (entries 3 and 4). High selectivity in favour of 11 a was achieved by the subsequent addition of camphorsulfonic acid (CSA), presumably through a thermodynamic double isomerization (entry 5). Next, we examined the effect of various phosphine ligands on the reaction selectivity. The use of Buchwald ligands such as L2 and L3 did not improve the selectivity for the formation of 11 a over 13 a (entries 6 and 7), whereas bulky phosphine L4 gave a lower 11 a/13 a ratio (entry 8). Remarkably, the use of triphenylphosphine and L5 resulted in a major improvement in regioselectivity favouring 11 a (> 20:1) albeit in lower yields (entries 9 and 10). To our delight, we found that the use of JackiePhos (L6) gave 11 a as the sole isomer in 98 % yield. After the establishment of the optimized conditions, we examined the broad applicability of the AuI-catalyzed DDA reaction. Several enynes 10 b–j were prepared and subjected to the reaction conditions (Table 2). Cyclization of 10 b (n = 2, R1 = H and R2 = Me) and 10 c (n = 3, R1 = H and R2 = Me) T 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim Angew. Chem. Int. Ed. 2017, 56, 6280 –6283 Angewandte Communications Table 1: Optimization of carbocyclization with gold in the formation of substituted angular core. Entry Ligand Loading [mol %] Ratio 11 a:12 a:13 a Yield [%][a] 1 2 3 4 5[b] 6[b] 7[b] 8[b] 9[b] 10[b] 11[b] L1 L1 L1 L1 L1 L2 L3 L4 Ph3PAuNTf2 L5 L6 2.5 1 0.5 0.1 1 1 1 1 1 1 1 6:6:1 6:6:1 6:6:1 6:6:1 13:0:1 12:0:1 9:0:1 5:0:1 > 20:0:1 > 20:0:1 > 20:0:1 98 98 51 18 98 98 98 98 68 49 98 (96)[c] [a] Determined by 1H NMR analysis of the crude reaction mixture using mesitylene as internal standard. [b] One equivalent of CSA was added to the reaction mixture only after all the starting material was consumed and stirred for 1 h. [c] Isolated yield. Table 2: Substrate scope for gold carbocyclyzation. Chemie provided the desired tricycles 11 b and 11 c in 79 % and 61 % yields, respectively. It is worth noting that the cyclization of enynes having terminal substituents 10 d (R1 = Me and R2 = H) and 10 e (R1 = Ph and R2 = H) afforded the desired tricycles 11 d and 11 e having four contiguous stereogenic centers in 91 % and 81 % yields, respectively. With regards to the cyclization of 10 f and 10 g, we found that the use of [L1AuNCMe]SbF6 led to full conversion and the desired angular cores 11 f and 11 g were generated in 93 % yield as the sole diastereisomer in both cases. However, AuI-catalyzed DDA of 10 h containing a cyclohexenyl unit gave tetracycle 11 h in 86 % yield as a 1:1 mixture of diastereomers. Cyclization of alkyne having a furyl group (10 i) gave the cycloadduct 11 i in 89 % yield. Interestingly, the cyclization of 10 j using [L6AuNCMe]SbF6 gave the naphthalene derivative 14 j in 74 % yield presumably through a cationic [1,2]-shift whereas the cyclization with [L1AuNCMe]SbF6 provided the desired compound 11 j in 91 % yield [Eq. (4)]. Both reactions were performed without the subsequent addition of CSA. To further demonstrate its synthetic utility, we applied the AuI-catalyzed dehydro Diels–Alder reaction to a concise synthesis of magellanine (7), an alkaloid isolated from the club moss Lycopodium Magellanicum.[10, 11] This natural alkaloid contains a tricyclic angular carbon framework with 6 contiguous stereogenic centers and it has been the subject of several synthetic investigations.[12] The key strategic disconnections made on 7 involved a carefully orchestrated C@C bond formation sequence. As such, the AuI-catalyzed DDA reaction of 15 would forge the C and D ring of 7 (Scheme 2). Scheme 2. Retrosynthetic analysis of (:)-magellanine (7). [a] Isolated yields, ratio 5-exo/6-endo and d.r. > 20:1. [b] Reaction run using 2 mol % of [L6AuNCMe]SbF6. [c] Reaction run using 1 mol % of [L1AuNCMe]SbF6. [d] No addition of CSA. Angew. Chem. Int. Ed. 2017, 56, 6280 –6283 The cycloadduct precursor 15 could arise from a stereoselective 1,4-conjugated addition between enal 16 and enyne 17. Finally, the bicyclic fragment 16 would be assembled by way of a one-pot Mitsunobu/Diels–Alder reaction between 18 and 19 followed by an oxidation/aldol sequence. As shown in Scheme 3, we started our synthesis by treatment of the homoallylic alcohol 18[13] with N,N,N,N- T 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim www.angewandte.org 6281 Communications Angewandte Chemie Scheme 3. Total synthesis of magellanine 7. Reagents and conditions: a) TMAD, TBP, 19, o-xylene, 0 8C; then BHT 150 8C. b) OsO4, NMO, NaIO4, THF:H2O, 20 8C. c) Piperidine, AcOH, PhMe, 20 8C. d) TIPSOTf, DMS, LiHMDS, THF, @78 8C. e) [L6AuNCMe][SbF6] (1 mol %) PhMe, 20 8C; then CSA (1 equiv). f) TBAF, 60 8C; then LiOH, H2O/THF, 140 8C. g) DMP, DCM, 20 8C. h) PtO2, H2, EtOAc, 20 8C. i) i-PrCO2Cl, NMM, Et3N, 25, PhMe, 0 8C; then 365 nm LED, O2, tert-dodecylmercaptan, 0 8C; then PPh3. j) DIAD, HCO2H PPh3, THF; then LiOH. k) Na, naphthalene, THF, @78 8C; then AcOH, formaldehyde, NaBH3CN, 20 8C. l) LDA (2 equiv), TMSCl (1 equiv), 30, THF, 0 8C; then HCl, 20 8C. TMAD = tetramethyl azodicarboxamide, TBP = tributylphosphine, BHT = butylated hydroxytoluene, NMO = N-methylmorpholine N-oxyde, THF = tetrahydrofuran, TIPS = triisopropylsilyl, DMS = dimethyl sulfide, CSA = camphorsulfonic acid, TBAF = tetrabutylammonium fluoride, DMP = Dess–Martin periodinane, DCM = dichloromethane, NMM = N-methylmorpholine, DIAD = diisopropyl azodicarboxylate, LDA = lithium diisopropylamide, TMS = trimethylsilyl. tetramethylazodicarboxamide (TMAD), n-tributylphosphine (TBP) and N-tosyl-allylamine 19 in o-xylene to give the corresponding triene 20 which upon heating generated the Diels–Alder adducts 21 as a mixture of diastereomer (1:1) in 70 % yield. A quantitative oxidative cleavage of the double bond using the Lemieux–Johnson protocol followed by an aldol condensation afforded the enal 16 in 54 % yield over two steps. Treatment of 16 with TIPSOTf and DMS followed by addition of the deprotonated enyne 17[7] with LiHMDS generated the 1,4-addition product 15 in 81 % yield as the sole diastereomer. With sufficient quantities of 15 in hand, we proceeded with the gold-catalyzed DDA reaction. As anticipated, the conversion of 15 to the desired tetracyclic 22 was achieved in 92 % yield in a highly regio- and diastereoselective manner (> 95:5) using [L6AuNCMe]SbF6 (1 mol %) (> 5 g were easily prepared through this operationally simple sequence). Tetracycle 22 was efficiently converted to the carboxylic acid 23 via a one-pot desilylation/saponification/decarboxylation procedure followed by a Dess–Martin oxidation. Several attempts to perform a selective hydrogenation of the olefin in the C ring were met with failure. We thus re-evaluated our strategy and opted for a complete double bond hydrogenation. Using Adams catalyst, compound 23 was completely converted to the saturated carboxylic acid 24 in 85 % yield. The conversion of the carboxylic acid moiety to a hydroxy group turned out to be very challenging. After a considerable experimentation, we adapted a protocol developed by Barton and Zard[14] for the radical oxidative decarboxylation of 24. The latter was converted to the corresponding N-oxime ester 6282 www.angewandte.org 26 which upon irradiation with UVA LED in the presence of O2 and tert-dodecylmercaptan followed by a treatment with PPh3 gave a 1:1 separable mixture of alcohols 27 and 28 in 55 % combined yield. The material was combined as a single diastereomer at this stage through conversion of 27 into 28 by a Mitsunobu reaction. Drawing inspiration from the work of Yan and co-workers,[12g] the N-methyl group was installed through a one-pot detosylation/reductive amination process in readiness for an oxidation using the Mukayama salt 30[15] to deliver (:)-magellanine 7 in 64 % yield.[16] In conclusion, we have developed an innovative and operationally facile methodology for the formation of carbocycles via a gold(I)-catalyzed cycloaddition. This reaction gives access to various complex angular fused-ring systems in high diastereoselectivities. The practicality of this AuI-catalyzed transformation was validated in the total synthesis of (:)-magellanine 7 which was accomplished in only 11 steps from alcohol 18, one of the shortest total syntheses known to date. Further applications of this transformation in natural product synthesis are currently ongoing and will be reported in due course.[17] Acknowledgements We thank the Natural Sciences and Engineering Research Council (Discovery grant to L.B. and for post-graduate scholarship PGS-D to P.M.), and the University of Ottawa for support of this research. T 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim Angew. Chem. Int. Ed. 2017, 56, 6280 –6283 Communications Conflict of interest The authors declare no conflict of interest. Keywords: Diels–Alder reaction · gold · homogeneous catalysis · magellanine · total synthesis How to cite: Angew. Chem. Int. Ed. 2017, 56, 6280 – 6283 Angew. Chem. 2017, 129, 6377 – 6380 [1] For selected recent reviews, see: a) R. W. Hoffmann, Synthesis 2006, 3531 – 3541; b) P. A. Wender, V. A. Verma, T. J. Paxton, T. H. Pillow, Acc. Chem. Res. 2008, 41, 40 – 49; c) K. C. Nicolaou, J. S. Chen, Chem. Soc. Rev. 2009, 38, 2993 – 3009; d) T. Newhouse, P. S. Baran, R. W. Hoffmann, Chem. Soc. Rev. 2009, 38, 3010 – 3021; e) P. A. Wender, B. L. Miller, Nature 2009, 460, 197 – 201; f) N. Z. Burns, P. S. Baran, R. W. Hoffmann, Angew. Chem. Int. Ed. 2009, 48, 2854 – 2867; Angew. Chem. 2009, 121, 2896 – 2910; g) I. S. Young, P. S. Baran, Nat. Chem. 2009, 1, 193 – 205; h) T. Gaich, P. S. Baran, J. Org. Chem. 2010, 75, 4657 – 4673; i) T. Newhouse, P. S. Baran, Angew. Chem. Int. Ed. 2011, 50, 3362 – 3374; Angew. Chem. 2011, 123, 3422 – 3435; j) W. R. Gutekunst, P. S. Baran, Chem. Soc. Rev. 2011, 40, 1976 – 1991; k) T. Brgckl, R. D. Baxter, Y. Ishihara, P. S. Baran, Acc. Chem. Res. 2012, 45, 826 – 839; l) C. A. Kuttruff, M. D. Eastgate, P. S. Baran, Nat. Prod. Rep. 2014, 31, 419 – 432; m) A. C. Jones, J. A. May, R. Sarpong, B. M. Stoltz, Angew. Chem. Int. Ed. 2014, 53, 2556 – 2591; Angew. Chem. 2014, 126, 2590 – 2628; n) A. Fgrstner, Angew. Chem. Int. Ed. 2014, 53, 8587 – 8598; Angew. Chem. 2014, 126, 8728 – 8740. [2] For selected reviews, see: a) C. Aubert, L. Fensterbank, P. Garcia, M. Malacria, A. Simonneau, Chem. Rev. 2011, 111, 1954 – 1993; b) N. Krause, C. Winter, Chem. Rev. 2011, 111, 1994 – 2009; c) M. Rudolph, A. S. K. Hashmi, Chem. Commun. 2011, 47, 6536 – 6544; d) M. Rudolph, A. S. K. Hashmi, Chem. Soc. Rev. 2012, 41, 2448 – 2462; e) C. Obradors, A. M. Echavarren, Acc. Chem. Res. 2014, 47, 902 – 912; f) Y. Zhang, T. Luo, Z. Yang, Nat. Prod. Rep. 2014, 31, 489 – 503; g) L. Fensterbank, M. Malacria, Acc. Chem. Res. 2014, 47, 953 – 965; h) A. Fgrstner, Acc. Chem. Res. 2014, 47, 925 – 938; i) R. Dorel, A. M. Echavarren, Chem. Rev. 2015, 115, 9028 – 9072. [3] P. Wessig, G. Mgller, Chem. Rev. 2008, 108, 2051 – 2063. [4] For Pd0-catalyzed DDA between enyne and yne, see: a) S. Saito, M. M. Salter, V. Gevorgyan, N. Tsuboya, K. Tando, Y. Yamamoto, J. Am. Chem. Soc. 1996, 118, 3970 – 3971; b) M. Rubin, A. W. Sromek, V. Gevorgian, Synlett 2003, 2265 – 2291; with gold(I), see: c) J. Barluenga, M. A. Fern#ndez-Rodr&guez, P. Garc&a-Garc&a, E. Aguilar, J. Am. Chem. Soc. 2008, 130, 2764 – 2765. [5] a) C. Nieto-Oberhuber, S. Llpez, A. M. Echavarren, J. Am. Chem. Soc. 2005, 127, 6178 – 6179; b) C. Nieto-Oberhuber, P. P8rez-Gal#n, E. Herrero-Glmez, T. Lauterbach, C. Rodr&guez, S. Llpez, C. Bour, A. Rosellln, D. J. C#rdenas, A. M. Echavarren, J. Am. Chem. Soc. 2008, 130, 269 – 279; c) N. Delpont, I. Escofet, P. P8rez-Gal#n, D. Spiegl, M. Raducan, C. Bour, R. Sinisi, A. Echavarren, Catal. Sci. Technol. 2013, 3, 3007 – 3012. [6] For other a) N. M8zailles, L. Rocard, F. Gagosz, Org. Lett. 2005, 7, 4133 – 4136; b) T. Shibata, R. Fujiwara, D. Takano, Synlett Angew. Chem. Int. Ed. 2017, 56, 6280 –6283 [7] [8] [9] [10] [11] [12] [13] [14] [15] [16] [17] Angewandte Chemie 2005, 2062 – 2066; c) M.-C. P. Yeh, W.-C. Tsao, B.-J. Lee, T.-L. Lin, Organometallics 2008, 27, 5326 – 5332; d) C.-M. Chao, M. R. Vitale, P. Y. Toullec, J.-P. GenÞt, V. Michelet, Chem. Eur. J. 2009, 15, 1319 – 1323; e) M. Morin, P. Levesque, L. Barriault, Beilstein J. Org. Chem. 2013, 9, 2625 – 2628. F. Barab8, P. Levesque, I. Korobkov, L. Barriault, Org. Lett. 2011, 13, 5580 – 5583. a) B. Baskar, H. J. Bae, S. E. An, J. Y. Cheong, R. H. Rhee, A. Duschek, S. F. Kirsch, Org. Lett. 2008, 10, 2605 – 2607; b) C. H. M. Amijs, V. Llpez-Carrilo, M. Raducan, P. P8rezGal#n, C. Ferrer, A. M. Echavarren, J. Org. Chem. 2008, 73, 7721 – 7730; c) P. Mauleln, R. M. Zeldin, A. X. Gonz#lez, F. D. Toste, J. Am. Chem. Soc. 2009, 131, 6348 – 6349; d) D. Benitez, E. Tkatchouk, A. Z. Gonzalez, W. A. Goddard III, F. D. Toste, Org. Lett. 2009, 11, 4798 – 4801; e) M. Alcarazo, T. Stork, A. Anoop, W. Thiel, A. Fgrstner, Angew. Chem. Int. Ed. 2010, 49, 2542 – 2546; Angew. Chem. 2010, 122, 2596 – 2600; f) W. Rao, D. Susanti, B. J. Ayers, P. W. Hong Chan, J. Am. Chem. Soc. 2011, 133, 15248 – 15251; g) Y. Wei, M. Shi, ACS Catal. 2016, 6, 2515 – 2524. For recent examples of gold(I)-catalyzed cycloaddition, see: a) H. Kusama, Y. Karibe, Y. Onizawa, N. Iwasawa, Angew. Chem. Int. Ed. 2010, 49, 4269 – 4272; Angew. Chem. 2010, 122, 4365 – 4368; b) J.-F. Brazeau, S. Zhang, I. Colomer, B. K. Corkey, F. D. Toste, J. Am. Chem. Soc. 2012, 134, 2742 – 2749. M. Castillo, L. A. Loyola, G. Morales, I. Singh, C. Calvo, H. L. Holland, D. B. Maclean, Can. J. Chem. 1976, 54, 2893 – 2899. For Lycopodium alkaloids synthesis using gold(I) catalysis, see: a) S. T. Staben, J. J. Kennedy-Smith, D. Huang, B. K. Corkey, R. L. LaLonde, F. D. Toste, Angew. Chem. Int. Ed. 2006, 45, 5991 – 5994; Angew. Chem. 2006, 118, 6137 – 6140; b) X. Linghu, J. J. Kennedy-Smith, F. D. Toste, Angew. Chem. Int. Ed. 2007, 46, 7671 – 7673; Angew. Chem. 2007, 119, 7815 – 7817. For total syntheses of magellanine, see: a) G. C. Hirst, T. O. Johnson, L. E. Overman, J. Am. Chem. Soc. 1993, 115, 2992 – 2993; b) J. P. Williams, D. R. St. Laurent, D. Friedrich, E. Pimard, B. A. Roden, L. A. Paquette, J. Am. Chem. Soc. 1994, 116, 4689 – 4696; c) C.-F. Yen, C.-C. Liao, Angew. Chem. Int. Ed. 2002, 41, 4090 – 4093; Angew. Chem. 2002, 114, 4264 – 4267; d) M. Ishizaki, Y. Niima, O. Hoshino, H. Hara, T. Takahashi, Tetrahedron 2005, 61, 4053 – 4065; e) T. Kozaka, N. Miyakoshi, C. Mukai, J. Org. Chem. 2007, 72, 10147 – 10154; f) S.-Z. Jiang, T. Lei, K. Wei, Y.-R. Yang, Org. Lett. 2014, 16, 5612 – 5615; g) K.W. Lin, B. Ananthan, S.-F. Tseng, T.-H. Yan, Org. Lett. 2015, 17, 3928 – 2940. Readily prepared in two steps from methyl sorbate, see: C. A. Miller, R. A. Batey, Org. Lett. 2004, 6, 699 – 702. D. H. R. Barton, S. D. G8ro, P. Holliday, B. Quiclet-Sire, S. Z. Zard, Tetrahedron 1998, 54, 6751 – 6756. T. Mukaiyama, J.-I. Matsuo, H. Kitagawa, Chem. Lett. 2000, 29, 1250 – 1251. The spectroscopic data for synthetic 7 are in agreement with those previously reported, see the Supporting Information. Experimental procedures and spectroscopic data for all new compounds can be found in the Supporting Information. Manuscript received: November 28, 2016 Final Article published: January 12, 2017 T 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim www.angewandte.org 6283 Angewandte Chem Assignment Selection of Article The article selected for this exercise is: A 11-Steps Total Synthesis of Magellanine through a Gold(I)-CatalyzedDehydro Diels–Alder Reaction, authored by McGee, Betournay, Barabe, and Barriault in 2017. Reaction Figure 1 is illustrating the chiral reaction identifies from the article. The reaction is a forward mechanism involving Dess-Martin oxidation, whereby the secondary alcohol is converted to a ketone. During the reaction, Dess-Martin periodinane (DMP) compound was used as the oxidizing agent. The reaction details of product 23 are shown in page S15. Figure 1: Chiral reaction for product 23, Ref: S15 Supporting Data Figure 2 illustrates the supporting information for the synthesis of product 23. It is purified via f ...
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