Original Mitsunobu-Triggered Sequence Involved in a One-Pot Domino Process toward Tetracyclic Systems Bearing a Bis-N,O-acetal Junction

J Org Chem. 2016 Oct 7;81(19):8837-8849. doi: 10.1021/acs.joc.6b01523. Epub 2016 Sep 16.

Abstract

Herein is reported an efficient, one-pot domino process through a 1,6-aza-Michael addition-triggered sequence and an original Mitsunobu-type concerted sequence for the synthesis of tetracyclic systems containing a bis-N,O-acetal junction. This methodology led to the construction of four new bonds, the cleavage of three C-O bonds, and the generation of an asymmetric center. Mitsunobu activation afforded final ring closure involving the creation of two bonds, which remains unprecedented among reported Mitsunobu-type sequences. The latter occurred in a regioselective fashion at the challenging C6-position of 2-pyridone intermediates. In the case of adequately substituted enantiopure amino alcohols, up to 95:5 of diastereoisomeric excess was achieved. Computational studies allowed the discrimination of a favored pathway for Mitsunobu sequence and supported the regioselectivity as well as the diastereoselectivity observed for this step.

Publication types

  • Research Support, Non-U.S. Gov't