Highly Enantioselective Iridium-Catalyzed Hydrogenation of α,β-Unsaturated Esters
作者:Jia-Qi Li、Xu Quan、Pher G. Andersson
DOI:10.1002/chem.201200907
日期:2012.8.20
α,β‐Unsaturated esters have been employed as substrates in iridium‐catalyzed asymmetric hydrogenation. Full conversions and good to excellent enantioselectivities (up to 99 % ee) were obtained for a broad range of substrates with both aromatic‐ and aliphatic substituents on the prochiral carbon. The hydrogenated products are highly useful as building blocks in the synthesis of a variety of natural
Enantioselective Synthesis of 2-Substituted 6- and 7-Membered Lactones via α-Alkylation of Lactone Hydrazones
作者:Dieter Enders、Robert Gröbner、Jan Runsink
DOI:10.1055/s-1995-4431
日期:1995.8
2-Alkyl-substituted lactones 4 were synthesized in good overall yields and high enantiomeric purities (ee=90-94%) by deprotonation and alkylation of the corresponding lactone SAMP-hydrazones 2 and subsequent oxidative cleavage of the product hydrazones 3 by ozonolysis. The lactone hydrazones 2, in turn, were prepared in good yields by silver promoted cyclization of Ï-chloroalkanohydrazides 1.