An efficient one‐pot N‐alkylation of benzimidazole and benzotriazole from carbonyl compounds and tosylhydrazide has been accomplished via copper powder‐catalyzed N—H bond insertion affording N‐alkylated products in good yields. The reaction can tolerate a wide range of carbonyl compounds, such as aryl, alkyl, heterocyclic and α,β‐unsaturated ketones, and aldehydes.
Reaction of β-keto phenylsulphone tosylhydrazones 2 with 2 eq. of DBU, at r.t. in dichloromethane, affords α,β-unsaturated ketone tosylhydrazones 4, via the tosylazoalkenes 3 obtained by 1,4-elimination of benzenesulfinic acid.
N-Tosylhydrazones generated in situ from cyclicketones smoothly underwent a [3 + 2] cycloaddition to afford saturated spirocyclic pyrazoles and further transformed to the fused analogues via a ringexpansion in certain cases. An inexpensive and renewable resource, calcium carbide, was utilized as the carbon source in the ringexpansion. The salient features of this reaction include widely available
A convenient method for the synthesis of indoles has been developed by the sequential orchestration of the cross-coupling reaction of o-haloaniline and PIFA oxidation of the resulting 2-alkenylanilines. A highlight of this two-step indolesynthesis is a modular strategy which is applicable to both acyclic and cyclic starting materials. Particularly noteworthy is the regiochemistry that is complementary