Pyridinium 1,4-zwitterionic thiolates as a useful class of sulfur-containing synthons: application to the synthesis of 2,5-dihydro-1,4,5-thiadiazepines

Abstract

A class of air-stable, odorless, easy-to-handle, and readily available sulfur-containing synthons that react with 1,2-diaza-1,3-dienes to afford 2,5-dihydro-1,4,5-thiadiazepines is described.

Direct Cyclopropanation of Quinolinium Zwitterionic Thiolates via Dearomative Reactions

“…On the basis of our experimental findings and previous studies, 4,7 a plausible pathway is depicted in Scheme 5. First, deprotonation of trimethylsulfoxonium iodide results in a sulfur ylide A under basic conditions (such as NaH), which could result in intermolecular nucleophilic attacks on the quinolinium zwitterionic thiolates…”

“…These pyridinium 1,4zwitterionic thiolates that have been developed as sulfurcontaining synthons can undergo distinct reaction modes (e.g., [3 + 2], [3 + 4], [5 + 1], and [5 + 2]) with a series of unsaturated bond molecules (e.g., alkynes, azoalkenes, arynes, and allenes). 7 Given our ongoing interest in cyclic organosulfur compounds, we developed isolable quinolinium zwitterionic thiolates, which were first reported by Bazgir's group and may serve as practical 1,5-dipoles in the synthesis of cyclic organosulfur compounds. 8 In this context, we wondered whether quinolinium zwitterionic thiolates could be used as an activated N-heteroarene to undergo the dearomative addition with sulfur ylides, affording 9b,10,10a,10b-tetrahydro-1H-cyclopropa [c] [1,4]thiazino [4,3-a]quinoline as the annulation products (Scheme 1).…”

Synthesis of Pyridothiazepines via a 1,5‐Dipolar Cycloaddition Reaction between Pyridinium 1,4‐Zwitterionic Thiolates and Activated Allenes

“…[4] These compounds can be easily prepared via a three‐component reaction between a dialkyl acetylenedicarboxylate, elemental sulfur, and pyridine, [5] and are air‐stable, odourless, easy‐to‐handle, and readily available. We envisaged that these compounds may be used as versatile sulfur‐containing synthons to synthesize organosulfur compounds via two reaction pathways (i. e., [3+m] and [5+m], Scheme 1), which have been demonstrated during the synthesis of thiadiazepines, [4a] thiophenes, [4b,c] pyrazoles, [4d] etc [4e–h] …”

Synthesis of Functionalized 4,1‐Benzothiazepines via a [4+3] Annulation between Aza‐o‐Quinone Methides and Pyridinium 1,4‐Zwitterionic Thiolates

“…Flash column chromatography was performed using silica gel (300-400 mesh). N-(ortho-chloromethyl)aryl amides 1 [17] and pyridinium 1,4-zwitterionic thiolates 2 [18] were prepared according to the representative methods. CCDC-2101212 (3 ja) and CCDC-2101213 (5 aa) contain the supplementary crystallographic data for this paper.…”