Multicomponent domino reactions of hydrazinecarbodithioates: concise access to 3-substituted 5-thiol-1,3,4-thiadiazolines

Abstract

Two classes of addition/cycloaddition cascade reactions of hydrazinecarbodithioate (1) have been developed under mild reaction conditions. Reaction of hydrazinecarbodithioate (1) with formaldehyde solution (2) and propiolic acid (3) gives 3-propargyl-5-thiol-2,3-dihydro-1,3,4-thiadiazoles (5) via a decarboxylative coupling/cycloaddition domino sequence. When propiolic acid (3) is switched to phenyl boronic acid (4), a petasis/cycloaddition domino reaction is instead observed, in which 3-benzyl-5-thiol-2,3-dihydro-1,3,4-thiadiazoles (6) are obtained. Both these reactions show a wide range of functional-group compatibility for propiolic acids and aryl boronic acids, and give the corresponding products in moderate to good yields.

Metal‐Free Decarboxylation of α,β‐Unsaturated Carboxylic Acids for Carbon–Carbon and Carbon–Heteroatom Coupling Reactions

“…It is noteworthy that when phenyl boronic acids were introduced instead of propiolic acids, 3‐benzyl‐5‐thiol‐2,3‐dihydro‐1,3,4‐thiadiazoles could be obtained via a Petasis/cycloaddition domino reaction (Scheme 6). [19] …”

Environmentally friendly domino multicomponent strategy for the synthesis of pyrroloquinolinone hybrid heterocycles

“…1 This protocol obviates the isolation and purication steps which leads to an improvement in the overall yield compared to classical multistep synthetic transformations in a single pot manipulation and represents an attractive synthetic method for building hybrid heterocyclic architectures. 2 Besides, this protocol is well suited for the production of structurally diverse hybrid heterocycles with multiple stereogenic centers and biologically relevant molecules. 3 Domino multicomponent reactions involving 1,3-dipolar cycloadditions are attractive in this connection as this reaction allows for the efficient assembly of biologically relevant vemembered heterocycles.…”