C-N Ring Construction: The Synthesis of Decursivine by Mascal and by Jia
Barry M. Trost and Justin Du Bois of Stanford University described (Org. Lett. 2011, 13, 3336. DOI: 10.1021/ol2010769) the cyclization of 1 to the activated aziridine 2. Liming Zhang of the University of California, Santa Barbara rearranged (Angew. Chem. Int. Ed. 2011, 50, 3236. DOI: 10.1002/anie.201007624) the propargylic amine 3 to the azetidinone 4, by N-H insertion of an intermediate Au carbene.
Xiao Zheng and Pei-Qiang Huang of Xiamen University effected (J. Org. Chem. 2011, 76, 4952. DOI: 10.1021/jo200600n) reductive coupling of 6 with 7 to deliver the ester 8. Eiji Tayama of Niigata University found (Tetrahedron Lett. 2011, 52, 1819. DOI: 10.1016/j.tetlet.2011.02.040) that 9 could be alkenylated with 10 with substantial retention of absolute configuration. Duncan J. Wardrop of the University of Illinois at Chicago, en route to a synthesis of (-)-Swainsonine, observed (Org. Lett. 2011, 13, 2376. DOI: 10.1021/ol2006117) high diastereocontrol in the cyclization of 12 to 13. Iain Coldham of the University of Sheffield also observed (J. Org. Chem. 2011, 76, 2360. DOI: 10.1021/jo2000868) substantial diastereoselection in the cyclization of 14 to 15.
Robert E. Gawley of the University of Arkansas established (Org. Lett. 2011, 13, 394. DOI: 10.1021/ol102682r) that exposure of metalated 16 to just 5 mol % of a chiral ligand was sufficient to enable enantioselective coupling, to deliver 17. Christian Nadeau of Merck Frosst effected (J. Am. Chem. Soc. 2011, 133, 2878. DOI: 10.1021/ja111540g) enantioselective addition to the pyridinium salt 19 to give 20. Jiyong Hong of Duke University observed (Org. Lett. 2011, 13, 796. DOI: 10.1021/ol103064f) that enantiomerically pure 21 cyclized to the cis diastereomer of 22. With the Hayashi catalyst, cyclization could be driven toward the trans diastereomer, 22, enabling the synthesis of (+)-Myrtine. Dawei Ma of the Shanghai Institute of Organic Chemistry found (Org. Lett. 2011, 13, 1602. DOI: 10.1021/ol200004s) that the Hayashi catalyst also directed the relative and absolute outcome in the addition of 24 to 23, to give the piperidine 25.
Donn G. Wishka of Pfizer/Groton devised (J. Org. Chem. 2011, 76, 1937. DOI: 10.1021/jo102475s) a practical route to the cis-substituted azepane 27, by Beckmann rearrangement of the enantiomerically-pure 26 followed by reduction and oxidative cleavage. Wen-Hua Chiou of the National Chung Hsing University formylated (Chem. Comm. 2011, 47, 3562. DOI: 10.1039/C0CC05646D) 28, to give, after cyclization, the bicyclic ketone 29.
Mark Mascal of the University of California, Davis crafted (Angew. Chem. Int. Ed. 2011, 50, 4445. DOI: 10.1002/anie.201006423) an elegant route to the antimalarial Decursivine (33), based on the Witkop cyclization of 32. Remarkably, Yanxing Jia of Peking University devised (Angew. Chem. Int. Ed. 2011, 50, 4447. DOI: 10.1002/anie.201100495) a nearly identical synthesis.