A Study of [3+2] Cycloaddition Reaction of Hydrazonoyl Chloride and β‐Oxodithioester Under Lewis Acid Catalysis: Stereoselective Synthesis of (Z)‐1,3,4‐Thiadiazol‐2(3H)‐Ylidenes.

Abstract

Hydrazonoyl chlorides underwent unprecedented stereoselective [3 + 2] cycloaddition reaction with β-oxodithioesters and β-oxothioamides under Lewis acid catalysis producing (Z)-1,3,4-thiadiazol-2(3H)-ylidenes in high yields. These products are obtained also with a base. Though same products are obtained in both these conditions, they involve different reaction mechanisms. In base mediated reactions, 1,3-dipolar cycloaddition of a nitrilimine to C=S is operative and in Lewis acid catalysed reactions, β-oxodithioester/β-oxothioamide undergoes addition-cyclization reactions with a hydrazonoyl chloride.

A decade update on the application of β-oxodithioesters in heterocyclic synthesis

“…Almost at the same time, Madabhushi's group reported the same [3 + 2] cycloaddition reaction of β-oxodithioesters and hydrazonoyl chlorides under BF 3 ·OEt 2 -catalyzed or base-catalyzed conditions to produce 1,3,4-thiadiazoles. 54…”

Novel Homoleptic and Heteroleptic Pt(II) β‐oxodithiocinnamic ester Complexes: Synthesis, Characterization, Interactions with 9‐methylguanine and Antiproliferative Activity

“…β-oxodithioesters are highly efficient intermediates in organic synthesis, and despite their differing reactivities, considered parallel synthons for β-ketoester chemistry. [1][2][3][4][5][6][7] Also, they exhibit keto-enol tautomerism (Figure 1), which is shifted towards the enol form due to the high electronegativity of the β-keto group that makes the α-protons more acidic. [1] The enol form is also stabilized by the intramolecular hydrogen bonding and the conjugated system (Figure 1A).…”

“…Synthons containing both electrophilic and nucleophilic centers have significant potential for developing more effective reaction pathways during the construction of various heterocyclic systems. [1][2][3][4] As a result of those active centers and the specific advantages of easy preparation and versatile reactivity, β-oxodithioesters have been widely applied as a valuable building block in the synthesis of several organosulfur moieties, in which sulfur acts either as an internal or external substituent. [1][2][3][4][5][6][7] In addition, βoxodithioesters have been employed as O,S-chelating ligands in the synthesis of several homo and heteroleptic transition metal complexes.…”

“…[1][2][3][4] As a result of those active centers and the specific advantages of easy preparation and versatile reactivity, β-oxodithioesters have been widely applied as a valuable building block in the synthesis of several organosulfur moieties, in which sulfur acts either as an internal or external substituent. [1][2][3][4][5][6][7] In addition, βoxodithioesters have been employed as O,S-chelating ligands in the synthesis of several homo and heteroleptic transition metal complexes. [8][9][10][11][12][13][14][15][16] Several zinc(II), cadmium (II), nickel(II), and copper (II) β-oxodithioester complexes have been reported by Singh and co-workers to catalyze the transformation of many organic reactions.…”

“… [1] Furthermore, β‐oxodithioesters contain polyfunctional groups with multi‐reactive centers including three nucleophilic and two electrophilic centers, as shown in (Figure 1B and 1C). Synthons containing both electrophilic and nucleophilic centers have significant potential for developing more effective reaction pathways during the construction of various heterocyclic systems [1–4] . As a result of those active centers and the specific advantages of easy preparation and versatile reactivity, β‐oxodithioesters have been widely applied as a valuable building block in the synthesis of several organosulfur moieties, in which sulfur acts either as an internal or external substituent [1–7] .…”