Ramchand T. Pardasani

New polymeric sulfide-borane complexes: convenient hydroborating and reducing reagents

New polymeric borane adducts have been synthesized from polymeric sulfides, which are solids with a minimal odour. The adducts contain a high concentration of borane, have significant stability and are soluble in THF. They act as hydroborating and reducing reagents with behaviour similar to that of borane-methyl sulfide, making them attractive borane sources.

Photochemical synthesis of novel 4,5,9,10-tetraaryl-tricyclo[6.2.0.03,6]decane-2,7-diones: a theoretical view of photodimerization

A sequence of photodimerization reactions of 1,5-diaryl-1,4-pentadien-3-ones have been carried out to produce 4,5,9,10-tetraaryl-tricyclo[6.2.0.03,6]decane-2,7-diones. The title compounds were characterized by means of infrared (IR), nuclear magnetic resonance (NMR) and mass spectrometric methods. The reaction proceeds via a diradical stepwise mechanism through the triplet excited state with asynchronous ring closure. Density functional theory calculations have been well established to probe the mechanism of photodimerization. The diradical mechanism for dimerization of chalcone proceeds via ring closure of the complex formed by two molecules.

A versatile route to benzodiazocine and spiropyran derivatives through chalcones

AbstractSyntheses of 3-(phenyl)-benzo[b]thiophene [2, 3-d][1,2] benzodiazocine derivatives have been accomplished by the reaction of 3-phenacylidine-2-benzo[b]thiophene-2-ones with o-phenylene diamine. The photolytic reaction with trans-stilbene resulted in the exclusive formation of spiro{2′,5′,6′-triphenyl-2H-pyran-4′,3}-benzo[b]thiophene-2-one derivatives. Theoretical calculations have been performed to study the mechanism and stereoselectivity of products. Good yield and broad scope of usable substrates of industrial relevance are other prominent features of the present methodologies. Graphical AbstractSyntheses of 3-(phenyl)-benzo[b]thiophene [2, 3-d][1,2] benzodiazocine derivatives by the reaction of 3-phenacylidine-2-benzo[b]thiophene-2-ones with o-phenylene diamine have been accomplished. A [4+2] photocycloaddition has been carried out to obtain spiro{20,50,60-triphenyl-2H-pyran-40,3}-benzo[b] thiophene-2-one derivatives from 3-phenacylidine-2-benzo[b]thiophene-2-ones and trans-stilbene.

Base-induced benzoyl migrations in Diels–Alder adducts of benzoyl-1,4-benzoquinones

Addition of buta-1,3-diene and trans-penta-1,3-diene to substituted benzoyl-1,4-benzoquinones affords the corresponding 4a-benzoyl-4a,5,8,8a-tetrahydro-1,4-naphthoquinones which in pyridine and pyridine–methanol, undergo [1,5] and [1,2] benzoyl shifts to give 2-benzoyl-5,8-dihydro-1,4-dihydroxynaphthalenes; the effects of para-substituents in the benzoyl group on the kinetices and regiospecificity of the migration are described.