Total Synthesis of (-)-Citreoisocoumarin, (-)-Citreoisocoumarinol, (-)-12- epi-Citreoisocoumarinol, and (-)-Mucorisocoumarins A and B Using a Gold(I)-Catalyzed Cyclization Strategy

N Arjunreddy Mallampudi; Utkal Mani Choudhury; Debendra K Mohapatra

doi:10.1021/acs.joc.9b03278

Total Synthesis of (-)-Citreoisocoumarin, (-)-Citreoisocoumarinol, (-)-12- epi-Citreoisocoumarinol, and (-)-Mucorisocoumarins A and B Using a Gold(I)-Catalyzed Cyclization Strategy

J Org Chem. 2020 Mar 20;85(6):4122-4129. doi: 10.1021/acs.joc.9b03278. Epub 2020 Mar 10.

Authors

N Arjunreddy Mallampudi¹, Utkal Mani Choudhury^{1

2}, Debendra K Mohapatra^{1

2}

Affiliations

¹ Department of Organic Synthesis and Process Chemistry, CSIR-Indian Institute of Chemical Technology, Hyderabad 500007, India.
² Academy of Scientific and Innovative Research (AcSIR), New Delhi 110025, India.

PMID: 32098474
DOI: 10.1021/acs.joc.9b03278

Abstract

A unified and concise first asymmetric total synthesis of (-)-citreoisocoumarin (2), (-)-citreoisocoumarinol (3), 12-epi-citreoisocoumarinol (4), and (-)-mucorisocoumarins A (5) and B (6) have been accomplished from the common intermediate (-)-6-O-methyl-citreoisocoumarin (1). Central to the synthetic approach is a regioselective gold(I)-catalyzed 6-endo-dig cyclization strategy for the construction of the isocoumarin skeleton. The other key steps in this approach included Sonogashira coupling, Tsuji-Wacker oxidation, Evans-Saksena's 1,3-anti-reduction, and Narasaka-Prasad's 1,3-syn-reduction. The synthetic results unambiguously confirmed the absolute configuration of the natural products mucorisocoumarins A and B as (-)-(10R,12S)-5 and (+)-(10S,12S)-6, respectively.

Publication types

Research Support, Non-U.S. Gov't