Stereoselective preparation of enaminone lithium dianions: Synthesis of N,N-dimethylcarbamoylenaminones
摘要:
A simple regio- and stereoselective synthesis of N',N-dimethylcarbamoylenaminones 2 by acylation of enaminone lithium dianions 1 '' with N,N-dimethylcarbamoyl chloride is reported, The mechanism for the stereoselective preparation of the enaminone lithium dianions 1 '' and successive acylation was investigated. The carbamoylenaminones 2 are selectively cyclized to 4-amino-2-pyranones 3 or hydrolyzed to carbamoyl diketones 4 in acidic conditions. (C) 1997 Elsevier Science Ltd.
Stereoselective alkylation of cyclic and acyclic chiral β-enamino ketones lithium dianions: synthesis of either (R)- or (S)-chiral 1,3-diketones.
作者:Giuseppe Bartoli、Marcella Bosco、Cristina Cimarelli、Renato Dalpozzo、Giovanni De Munno、Gianni Palmieri
DOI:10.1016/s0957-4166(00)80373-0
日期:1993.7
synthesis of either (R)- or (S)-chiral 1,3-diketones through asymmetric γ alkylation reaction of cyclic and acyclic chiral β-enamino ketones was here performed. The alkylation takes place with good yields and high d.e. in HMPA/THF. Both the pure enantiomers of 1,3-diketones can be formed by simple hydrolysis of the epimeric β-enamino ketones obtained with this method, choosing the suitable synthetic strategies
The gamma-alkylation of the chiral beta-enamino ketones (1) has been obtained with good yields and d.e. on the si face of the lithium dianion intermediate.