A Modular Olefination of Aldehydes with Thiols as Coupling Partners

Abstract

Olefins range amongst the most important motifs in organic chemistry. Hence, the development of novel olefin syntheses has remained a constant field of research in synthetic chemistry to date. Herein, we report the development of a modular olefination that converts aldehydes into olefins with thiols as reaction partners. The simple, transition metal‐free protocol proceeds via an unsymmetrical bissulfone intermediate which is converted into the respective alkene in a Ramberg‐Bäcklund‐type process. Differently substituted olefins can be synthesized from readily available starting materials in typically good yields and stereoselectivities using basic laboratory chemicals exclusively. Complementary reaction conditions differing in the choice of solvent favor the E/Z‐products respectively under kinetic control rendering this protocol an interesting economical addition to the family of olefin syntheses.

Synthesis of Stilbenes by Cyanide/Base-Mediated Coupling of Benzylic Chlorides and Alcohols

“…13 (E)-1-Methoxy-3-styrylbenzene (11) 13 Isolated by flash column chromatography (5% EtOAc in hexane; R f = 0.32); clear oil; yield: 113 mg (54%). (E)-1-Styrylnaphthalene (12) 33 Isolated by flash column chromatography (5% EtOAc in hexane; R f = 0.72); pale yellow oil; yield: 134 mg (58%). 1 H NMR (400 MHz, CDCl 3 ):  = 8.24 (d, J = 7.8 Hz, 1 H), 7.94-7.86 (m, 2 H), 7.82 (d, J = 8.2 Hz, 1 H), 7.77 (d, J = 7.1 Hz, 1 H), 7.63 (d, J = 7.0 Hz, 2 H), 7.59-7.47 (m, 3 H), 7.42 (t, J = 7.7 Hz, 2 H), 7.32 (t, J = 7.3 Hz, 1 H), 7.17 (d, J = 16.0 Hz, 1 H).…”