Intra‐ and Intermolecular Oxa‐Pictet–Spengler Cyclization Strategy for the Enantioselective Synthesis of Deoxy Analogues of (+)‐Nanomycin A Methyl Ester, (+)‐Eleutherin, (+)‐Allo‐Eleutherin, and (+)‐Thysanone

Abstract

Abstract Enantioselective synthesis of deoxy analogues of pyranonaphthoquinone antibiotics (+)‐nanomycin A methyl ester, (+)‐eleutherin, (+)‐allo‐eleutherin, and (+)‐thysanone was achieved in good overall yield with high enantio‐ and diastereoselectivity from the common intermediate ( R )‐3‐(2,5‐dimethoxyphenyl)propane‐1,2‐diol. The intramolecular oxa‐Pictet–Spengler cyclization of 6‐aryl‐1,3‐dioxolone was developed for the first time and utilized in the enantioselective synthesis of (+)‐deoxynanomycin A methyl ester, whereas the intermolecular oxa‐Pictet–Spengler cyclization strategy was applied to the enantioselective synthesis of deoxy analogues of (+)‐eleutherin, (+)‐allo‐eleutherin, and (+)‐thysanone.