Synthesis of Pyrido[2, 3-a]phenoxazines and Pyrido[2, 3-a]phenothiazines via Successive SN Ar Processes

A four-step cascade reaction involving O[1,3] sigmatropic shift and Smiles rearrangements as key steps

4-Nitroaryl halides and N-acyl-N-arylhydroxyamines undergo cascade aromatic nucleophilic substitution-O[1,3] sigmatropic shift-Smiles rearrangement-amide and ester exchange reaction, affording 2-((4-nitroaryl)amino)aryl carboxylates.

Transition-Metal-Free Synthesis of N-Arylphenothiazines through an N- and S-Arylation Sequence

An efficient synthetic method of N-arylphenothiazines from o-sulfanylanilines under transition-metal-free conditions is disclosed. An N- and S-arylation sequence of o-sulfanylanilines enabled us to synthesize a wide variety of N-arylphenothiazines. In particular, one-pot synthesis of N-arylphenothiazines was accomplished from easily available modules through preparation of o-sulfanylanilines by thioamination of aryne intermediates and following N- and S-arylation sequence.

Simple Synthesis of Fused Thiazolo[4,5-b]pyridines through Successive SNAr Processes

A convenient process is described for the synthesis of novel thiazolo[4,5-b]pyridines fused with triazole or pyrimidine rings. The base-promoted reactions of 2-chloro-3-nitropyridines with 1,3-(S,N)-binucleophiles (triazole-5-thiols, 4-oxopyrimidine-2-thiones) resulted in nucleophilic substitution of the chlorine atom and subsequent S–N-type Smiles rearrangement followed by nucleophilic substitution of the nitro group. Reactions with pyrimidine-2-thiones were carried out as one-pot processes while, in the case of triazole-5-thiols, isolation of intermediate substitution products was found to be preferable.