Enantioselective Synthesis of Alcohols and Amines: The Morken Synthesis of Indolizidine 209D
René Peters of the Universität Stuttgart achieved high ee in the rearrangement of the N-oxide 1 to the tertiary alcohol 2 (Angew. Chem. Int. Ed. 2020, 59, 10944. ). Kazunori Koide of the University of Pittsburgh showed that NaBH4 in the presence of catalytic BINOL reduced the enone 3 to the allylic alcohol 4 in high ee (J. Org. Chem. 2020, 85, 4637. ).
Guozhu Zhang of the Shanghai Institute of Organic Chemistry assembled the allylic alcohol 8 by the three-component combination of the alkyne 5, the aldehyde 6 and the iodide 7 (Org. Lett. 2020, 22, 656. ). Gregory C. Fu of Caltech prepared the ester 11 by coupling the alkene 9 with the racemic bromide 10 (J. Am. Chem. Soc. 2020, 142, 5870. ).
Osamu Onomura of Nagasaki University prepared the tosylate 13 in high ee by the monosulfonylation of the prochiral diol 12 (Chem. Asian. J. 2020, 15, 840. ). Nicolai Cramer of the Ecole Polytechnique Fédérale de Lausanne reduced the methoxime 14 selectively to the methoxyamine 15 (Science 2020, 368, 1098. ). Eelco Ruijter of the Vrije Universiteit Amsterdam used an enantioselective Pd catalyst to cyclize the bis amide 16 to the allylic amine 17 (J. Org. Chem. 2020, 85, 12058. ). Wei-Liang Duan of Yangzhou University effected enantioselective C-H functionalization of 18, leading to the α-nitro lactam 19 (Chem. Commun. 2020, 56, 2292. ).
Fa-Guang Zhang and Jun-An Ma of Tianjin University added the enamide 21 to the imine 20, leading to the β-amino ketone 22 (J. Org. Chem. 2020, 85, 5580. ). Xiaoqing Cai of Sun Yat-sen University assembled the α-amino acid derivative 25 by alkylating the azlactone 23 with the activated cyclopropane 24 (Tetrahedron Lett. 2020, 61, 151694. ). Zhengfeng Zhang and Wanbin Zhang of Shanghai Jiao Tong University used a bicyclic imidazole to mediate the direct enantioselective acylation of the protected amino acid 26 with 27, leading to the α-tetrasubstituted α-amino acid derivative 28 (Chem. Sci. 2020, 11, 4801. ). Wei Du and Ying-Chun Chen of Sichuan University assembled the α-tetrasubstituted α-amino acid derivative 31 by alkylating the alkyne 30 with the pyrazoledione-derived ketimine 29 (Org. Lett. 2020, 22, 4732. ).
Indolizidine 209D (35), isolated from the neotropical "poison dart" frog, inhibits neuromuscular transmission. James P. Morken of Boston College established the absolute configuration of the key intermediate amine 34 by coupling the iodide 32 with the alkenylboron "ate" complex 33 (Org. Lett. 2020, 22, 666. ).