A Multi‐Component Reaction in the Morita­–Baylis–Hillman Route

Abstract

A facile stereoselective synthesis of trisubstituted (Z)/(E)‐alkenes containing a functionalized thioether unit has been accomplished by using a new three‐component tetramolecular reaction (ABCB′‐type) following a Morita–Baylis–Hillman (MBH) route. Syntheses beginning with preformed MBH adducts yield similar results (ABC‐type reaction) and broaden the scope of application. Suitably substituted aromatic aldehydes result in the formation of 3‐substituted‐2H‐thiochromenes in high yield.

Six-Membered Ring Systems

“…Synthesis of a range of 2H-thiochromenes is accomplished when 2,2′-dithiodibenzaldehyde reacts with electron-deficient alkenes in the presence of DBU or triphenylphosphine, but when used together as a dualcatalyst system, the overall yields are improved and the reaction time consistently reduced (13SC1837). The formation of other 2H-thiochromenes by a three-component reaction of o-substituted (halo and nitro groups) benzaldehydes, carbon disulfide, and electron-deficient vinyl compounds is efficiently catalyzed by DABCO (13EJO4816). The regioselectivity of the gold-catalyzed cyclization of the o-alkynyl benzothioamide 60 is controlled by the oxidation state of the metal: an Au(I) promoter led to an unusual 5-exo-dig cyclization to afford a rare example of an acyclic (aryl)(heteroaryl) carbene gold complex 61; an Au(III) catalyst induced a 6-endo-dig ring closure for the preparation of a cyclic 6-membered mesoionic carbene gold complex 62 (Scheme 89) (13AGE758).…”

Six-Membered Ring Systems: With O and/or S Atoms

“…The formation of other 2H-thiochromenes by a three-component reaction of o-substituted (halo and nitro groups) benzaldehydes, carbon disulfide, and electron-deficient vinyl compounds is efficiently catalyzed by DABCO (13EJO4816). The regioselectivity of the gold-catalyzed cyclization of the o-alkynyl benzothioamide 60 is controlled by the oxidation state of the metal: an Au(I) promoter led to an unusual 5-exo-dig cyclization to afford a rare example of an acyclic (aryl)(heteroaryl) carbene gold complex 61; an Au(III) catalyst induced a 6-endo-dig ring closure for the preparation of a cyclic 6-membered mesoionic carbene gold complex 62 (Scheme 89) (13AGE758).…”