Highly Efficient Asymmetric Access to 1-Azaspiro[4.4]nonane Skeleton
作者:Jacques Royer、Loïc Planas、Joëlle Pérard-Viret、Mohamed Selkti、Alain Thomas
DOI:10.1055/s-2002-34232
日期:——
Vinylogous Mukaiyama aldol type reaction of chiral non-racemic silyloxypyrroles followed by acidic treatment affords an efficient asymmetric access to 1-azaspiro[4.4]nonanes in high diastereoisomeric excess (up to 79%).
Chiral 1,2,3‐Triazolium Salt Catalyzed Asymmetric Mono‐ and Dialkylation of 2,5‐Diketopiperazines with the Construction of Tetrasubstituted Carbon Centers
作者:Ju‐Song Yang、Ka Lu、Chen‐Xiao Li、Zu‐Hang Zhao、Xiao‐Ming Zhang、Fu‐Min Zhang、Yong‐Qiang Tu
DOI:10.1002/anie.202114129
日期:2022.2.21
Chiral spirocyclic-amide-derived triazolium salts were used as new phase-transfer organocatalysts for asymmetric alkylation to construct 2,5-diketopiperazine motifs containing one or two tetrasubstituted carbon centers in high yields with excellent cis-diastereoselectivity and enantioselectivity. Control experiments and DFT calculations revealed the possible reaction mechanism and the origins of the
Efficient access to enantiomerically pure rigid diamines
作者:Loı̈c Planas、Joëlle Pérard-Viret、Jacques Royer
DOI:10.1016/j.tetasy.2004.06.011
日期:2004.8
Asymmetric spiro cyclization of a pyrrolidine derivative was used as a key step for constructing novel rigid diamines. A selected example has proved its utility as a chiral nonmetallic catalyst in a Michael reaction.
Stereoselective Synthesis of (−)-Cephalotaxine and C-7 Alkylated Analogues
作者:Loïc Planas、Joëlle Pérard-Viret、Jacques Royer
DOI:10.1021/jo049884l
日期:2004.4.1
A total asymmetric synthesis of (−)-cephalotaxine is reported. The chemistry of α,β-unsaturated γ-lactams was used to access the 1-azaspiro[4.4]nonane skeleton in enantiomerically pure form via a stereocontrolled semipinacolic rearrangement of an α-hydroxyiminium ion. This spiro compound was transformed into (−)-cephalotaxine without any racemization or epimerization by following the racemic synthesis