Pot-Economy Autooxidative Condensation of 2‑Aryl-2-lithio-1,3-dithianes

• Published in: Journal of organic chemistry Vol. 83; no. 4; pp. 1948 - 1958
• Main Authors: Vale, João R, Rimpiläinen, Tatu, Sievänen, Elina, Rissanen, Kari, Afonso, Carlos A. M, Candeias, Nuno R
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 16-02-2018
• ISSN: 0022-3263; 1520-6904
• DOI: 10.1021/acs.joc.7b02896

The autoxidative condensation of 2-aryl-2-lithio-1,3-dithianes is here reported. Treatment of 2-aryl-1,3-dithianes with n-BuLi in the absence of any electrophile leads to condensation of three molecules of 1,3-dithianes and formation of highly functionalized α-thioether ketones orthothioesters in 51–89% yields upon air exposure. The method was further expanded to benzaldehyde dithioacetals, affording corresponding orthothioesters and α-thioether ketones in 48–97% yields. The experimental results combined with density functional theory studies support a mechanism triggered by the autoxidation of 2-aryl-2-lithio-1,3-dithianes to yield a highly reactive thioester that undergoes condensation with two other molecules of 2-aryl-2-lithio-1,3-dithiane.