A visible‐light induced radical reaction of vinyl azides and α‐carbonyl benzyl bromides was developed, which provides an efficient route to polysubstituted quinolines via a C C and C N bond formation sequence.
This work describes acylation reactions facilitated by a type of heterocycle‐based acyl transfer agent, 2‐acyloxypyridazinone. Reactions of 2‐acyloxypyridazinone with carboxylic acids yield mixed carbonic anhydride intermediates, which are reactive and could be coupled with a wide range of substrates including acids, amines, alcohols, and thiols. The wide substrate scope, ease of operation (no additive or catalyst), storage and handling stability, and atom‐efficiency from recycling the heterocycle carrier make the reported acylating agent attractive for acylation‐based coupling reactions.
A general protocol for the chemoselectivity‐controlled C C and C S coupling reactions of di(hetero)aryl disulfides with Grignard reagents catalyzed by ferrocene and palladium acetate has been developed. Ferrocene favored the formation of C S coupled products at low temperature, whereas C C bond couplings were favored when palladium acetate was used. All the reactions proceeded with excellent chemoselectivity and in good yields under mild conditions, and a library of molecules with pyridine and pyrimidine scaffolds was produced.
Iodocyclization of ethynyl methyl sulfides gives 3‐iodo‐2‐thiomethyl heterocycles, setting up the synthesis of thieno‐fused systems through a subsequent iteration of alkyne coupling and iodocylization. This approach can also be exploited in the synthesis of polyfused thiophenes. In developing this protocol it was necessary to address issues associated with unfavourable electronic bias and redox sensitivity in some substrates. The manner in which these have been addressed should prove useful elsewhere in iodocyclization chemisty.
An organocatalytic enantioselective sulfur‐Michael addition of thioacetic acid to arylmethylidenemalonates was developed with high yields and up to 97% enantiomeric excess. Both enantiomers of the products were accessible with two different organocatalysts. The current method provides the first, practical, and convenient preparation of enantiomerically enriched acetylthiomethylmalonate derivatives.
Polysubstituted furans were obtained with excellent yields via the electrophilic alkynylation of 1,3‐dicarbonyl compoundsws with phenyl‐ or ester‐substituted brominated alkynes. The reaction is catalyzed by the inexpensive and readily available catalyst, cobalt(II) chloride, and has a wide substrate scope. The C(sp) C(sp3) coupling occurs under mild conditions with short reaction times and does not require an inert atmosphere or ligands. It is proposed that the reaction proceeds through a chelation complex of cobalt(II) with the deprotonated 1,3‐dicarbonyl compound.
