Asymmetric Carbene C–O Insertion Reaction Using Optically Active Bipyridine-Copper Complex as a Catalyst. Ring Expansion of Oxetanes to Tetrahydrofurans
Chiral bipyrindine and biquinoline ligands: Their asymmetric synthesis and application to the synthesis of trans-whisky lactone
摘要:
Chiral bipyrindine and biquinoline which have been reported to be efficient Ligands for the construction of chiral copper catalysts, were synthesized enantioselectively by rising Mn-salen catalyzed asymmetric epoxidation as a key step. Enantioselective synthesis of trans-whisky lactone was then achieved by way of enantiospecific ring expansion reaction of oxetane with a chiral copper catalyst bearing the bipyrindine Ligand as a chiral source.
Enantiopsecific Ring Expansion of Oxetanes: Stereoselective Synthesis of Tetrahydrofurans
作者:Tsutomu Katsuki、Katsuji Ito、Miwa Yoshitake
DOI:10.3987/com-95-s35
日期:——
Enantiospecific ring expansion of oxetanes to tetrahydrofurans with diazoacetic acid ester was found to be catalyzed by the copper complex of (7R,7'R)-7,7'-di(1-tert-butyldimethylsiloxy-1-methylethyl)-6,6',7,7'-tetrahydro-5H,5'H-2,2'-bi-1,1'-pyrindine (4). For example, the reaction of (R)-2-phenyloxetane of 89% ee and tert-buryl diazoacetate with Cu-4 complex as a catalyst provided (2S,3R)-tert-butyl 3-phenyltetrahydrofuran-2-carboxylate of 92% ee as a major product, while that of (S)-2-phenyloxetane of 85% ee provided (2S,3S)-tert-butyl 3-phenyltetrahydrofuran-2-carboxylate of 93% ee as a major one.