BF₃·OEt₂ catalyzed S–H insertion reactions of α-diazo imidamides and enolizable thioamides under metal-free conditions

Abstract

BF3•OEt2 Catalyzed S-H insertion reactions of α-diazo imidamides and substituted thioureas / thiosemicarbazones / cyclic thioamides were demonstrated to furnish the corresponding S-H insertion products. This method features wide substrate...

Acid‐catalyzed One Pot Synthesis of Thiazolo[4,5‐b]indolamines from α‐Diazoimidamides and Thioureas

“…Our study was based on our previous knowledge [20] about the Lewis acid catalyzed reactions of α‐diazoimidamides 1 and thioamides. Initially, the reaction of equimolar amount of α‐diazoimidamide 1 and N ‐phenylthiourea 2 was performed at room temperature in the presence of 10 mol% of BF 3 ⋅ OEt 2 provided the S−H insertion product [20] 4 (Table 1, entry 1).…”

“…Our study was based on our previous knowledge [20] about the Lewis acid catalyzed reactions of α‐diazoimidamides 1 and thioamides. Initially, the reaction of equimolar amount of α‐diazoimidamide 1 and N ‐phenylthiourea 2 was performed at room temperature in the presence of 10 mol% of BF 3 ⋅ OEt 2 provided the S−H insertion product [20] 4 (Table 1, entry 1). Compounds 1 and 2 were stirred at room temperature in the presence of a catalytic amount of BF 3 ⋅ OEt 2 and p ‐TSA to furnish the presence of a new product 3 along with insertion product 4 (Table 1, entry 2).…”

Concise Synthesis of Thiazolo[4,5‐b]indoles via Ring Switch/Cyclization Sequences

“…In 2020, Zhang and co‐workers reported the first construction of thiazolo[4,5‐ b ]indoles through a Suzuki‐Miyaura cross coupling reaction of 5‐bromothiazole with 2‐nitrophenyl boronic acid (sp 2 ‐type: Scheme 1A) [7] . In 2023, Muthusamy and co‐workers reported a BF 3 ⋅ OEt 2 ‐catalyzed synthesis of aminothiazolo[4,5‐ b ]indoles from α‐diazoimidamides and thioureas (sp 2 ‐type: Scheme 1B) [8] . The use of thioureas was necessary to promote the nucleophilic attack at the C3‐position of the indole ring, and successive cyclization gave amino‐substituted thiazolo[4,5‐ b ]indoles.…”