Highly convergent one-pot four-component regioselective synthesis of 4H-benzo[f]chromenes via annulation of β-oxodithioesters

Synthesis and structural features of indium(III) furan-2-thiocarboxylates showing efficient catalytic activity toward multicomponent reactions via Knoevenagel condensation

A series of furan-2-thiocarboxylate complexes of indium(III), Et3NH[In(SCOf)4] (1), iPr2NH2[In(SCOf)4] (2), [In(2,2'-bipy)(SCOf)3] (3a), and [In(1,10-phen)(SCOf)3] (3b), have been synthesized and structurally characterized. Complex 4, [In(TMEDA)(SCOf)(SH)2], was obtained by the partial hydrolysis of [In(TMEDA)(SCOf)3] (3). Heterobimetallic complexes [(SCOf)2In(μ-SCOf)2Cu(PPh3)2] (5) and [(SCOf)2In(μ-SCOf)2Ag(PPh3)2] (6), were also synthesized and characterized. In an attempt to synthesize the binary compound, In(SCOf)3 (7), a thioester fCOSCH2SCOf (8) was obtained serendipitously; thus, a novel convenient approach for thioester synthesis is introduced. The catalytic activities of all the complexes were assessed for Knoevenagel condensation and Knoevenagel initiated MCRs for the synthesis of chromene and imidazopyrimidine derivatives and it was found that complex 2 is a very efficient catalyst (much superior to the previously reported ones).

ortho-Quinone methide (o-QM): a highly reactive, ephemeral and versatile intermediate in organic synthesis

In this critical review, we provide a comprehensive view of the chemistry of ortho-quinone methides as versatile reactive intermediates in organic synthesis.

Recent developments of ketene dithioacetal chemistry

Ketene dithioacetals are versatile intermediates in organic synthesis. Extensive research, since the last decade, has given rise to new prospects in their chemistry. The objective of this review is twofold: first, to highlight the new prospects in the chemistry of functionalized ketene dithioacetals, and second, to provide an intrinsic link between ketene dithioacetal groups and a variety of other functional groups, which has brought out many new facts that will assist in future designs.

Multicomponent assembly of 2-amino-4-substituted 4H-chromenes using cyclic Michael donors

An efficient one-pot synthesis has been disclosed to access a series of 2-amino-4-substituted 4H-chromenes from salicylaldehyde, malononitrile, and a few cyclic nucleophiles using indium trichloride as a catalyst. This methodology affords high yields of products in a shorter reaction time.