Synthesis of enantioenriched indene-derived bicyclic alcohols and tricyclic cyclopropanes via (−)-sparteine-mediated lithiation of a racemic precursor and kinetic resolution during the cyclocarbolithiation
摘要:
By treatment of the racemic 3-(indenyl)alkyl carbamate rac-8 with sec-BuLi-(-)-sparteine, cyclocarbolithiation occurs, which is accompanied by kinetic resolution during the cyclisation step. After addition of electrophiles, the stereohomogeneous optically active benzobicyclo[3.3.0]octenols of type 13 are obtained. Increasing the temperature from - 78 to - 40 degreesC or the application of TMEDA instead of (-)-sparteine yields the formation of the tricyclic cyclopropane 14. (C) 2001 Elsevier Science B.V. All rights reserved.
Synthesis of enantioenriched indene-derived bicyclic alcohols and tricyclic cyclopropanes via (−)-sparteine-mediated lithiation of a racemic precursor and kinetic resolution during the cyclocarbolithiation
摘要:
By treatment of the racemic 3-(indenyl)alkyl carbamate rac-8 with sec-BuLi-(-)-sparteine, cyclocarbolithiation occurs, which is accompanied by kinetic resolution during the cyclisation step. After addition of electrophiles, the stereohomogeneous optically active benzobicyclo[3.3.0]octenols of type 13 are obtained. Increasing the temperature from - 78 to - 40 degreesC or the application of TMEDA instead of (-)-sparteine yields the formation of the tricyclic cyclopropane 14. (C) 2001 Elsevier Science B.V. All rights reserved.