Regioselective Synthesis of Tetrahydrothiochromen-5-ones via a One-Pot Three-Component Solvent-Free Domino Protocol

Access to Fully Substituted Thiazoles and 2,3-Dihydrothiazoles via Copper-Catalyzed [4 + 1] Heterocyclization of α-(N-Hydroxy/aryl)imino-β-oxodithioesters with α-Diazocarbonyls

An efficient chemoselective practical route to fully substituted thiazoles and 2,3-dihydrothiazoles has been devised by [4 + 1] heterocyclization of α-(N-hydroxy/aryl)imino-β-oxodithioesters with in situ generated Cu-carbenoids of diazocarbonyls. The α-(N-hydroxy/aryl)imino-β-oxodithioesters are readily accessible by the reaction of β-oxodithioesters with nitrous acid/nitrosoarenes. The overall transformation involves sequential N-O/C-N bonds cleavage followed by cascade C-N/C-S bonds formation in one-pot. This new strategy allows full control over the introduction of various sensitive functional groups at different positions of the thiazole ring, broadening the arsenal of synthetic methods to obtain such scaffolds.

Synthesis of polysubstituted 3,4-dihydro-2H-thiopyrans by regioselective annulation of 3,3-disubstituted allylic alcohols with a β-oxodithioester

Polyfunctionalized 3,4-dihydro-2H-thiopyrans were obtained in high yields via the regioselective annulation of 3,3-disubstituted allylic alcohols with a β-oxodithioester under BF₃·Et₂O catalysis.

Switching Selectivity of α-Enolic Dithioesters: One Pot Access to Functionalized 1,2- and 1,3-Dithioles

An operationally simple cascade protocol has been developed for the construction of 1,2- and 1,3-dithiole derivatives from α-enolic dithioesters. 1,2-Dithioles are achieved by the reaction of dithioesters with elemental sulfur in the presence of InCl₃ under solvent-free conditions. 1,3-Dithioles have been constructed via DABCO mediated self-coupling of dithioesters in open air enabling the formation of two new C-S bonds and one ring in a single operation in contiguous fashion. The reactions proceeded smoothly affording the desired sulfur-rich heterocycles in good to excellent yields, exhibiting gram-scale ability and broad functional group tolerance utilizing easy to handle cheap and easily available reagents. The probable mechanisms for the formation of 1,2- and 1,3-dithioles from α-enolic dithioesters have been suggested.

Bridging homogeneous and heterogeneous catalysis with CAN·SiO2as a solid catalyst for four-component reactions for the synthesis of tetrasubstituted pyrroles

The attractive features of this methodology are newer and greener methods, simple procedures, reusability and high efficiency of the catalyst and easy workability.

Molybdate sulfuric acid (MSA): an efficient reusable catalyst for the synthesis of tetrahydrobenzo[4,5]imidazo[2,1-b]quinazolin-1(2H)-ones under solvent-free conditions and evaluation of their in vitro bioassay

The attractive features of this methodology are green and easy workability with high product yields. All the title compounds have good to excellent anti-oxidant and anticancer activity.

2-Methylindole as an indicative nucleophile for developing a three-component reaction of aldehyde with two different nucleophiles

2-Methylindole was used as an indicative nucleophile for rapid screening of MCRs of aldehydes with two different nucleophiles. By removal of some samples that have characteristic color associated with the generation of di(indolyl)methane derivatives the difficulties encountered in the product analysis were alleviated significantly.

DMAP-promoted domino annulation of β-ketothioamides with internal alkynes: a highly regioselective access to functionalized 1,3-thiazolidin-4-ones at room temperature

One-pot DMAP-mediated regioselective access to functionalized 1,3-thiazolidin-4-ones has been achieved via annulation of β-ketothioamides with internal alkynes.

In(OTf)3-catalysed one-pot versatile pyrrole synthesis through domino annulation of α-oxoketene-N,S-acetals with nitroolefins

An operationally simple and efficient one-pot direct access to pyrroles has been achieved by annulation of α-oxoketene-N,S-acetals with β-nitrostyrenes catalyzed by In(OTf)₃under solvent-free conditions.

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.