Sukanta Bhattacharyya

Titanium(IV) isopropoxide and sodium borohydride : a reagent of choice for reductive amination

Abstract The preliminary results on the novel use of titanium(IV) isopropoxide and sodium borohydride in reductive amination reactions are reported. A highly efficient and mild procedure for reductive aminations of formaldehyde with a variety of primary and secondary amines is described.

Stereoselective synthesis of cis-A/B octahydrophenanthrene skeleton related to diterpenes via reductive alkylation in anhydrous ammonia

Abstract 7-Methoxy-1,1,4aβ-trimethyl-1,2,3,4aβ,9,10,10aβ-octahydrophenanthrene ( 5 , a skeletal representative of several diterpenes, has been synthesised stereoselectively through reductive methylation of the ∝,β-unsaturated ketone 14 in anhydrous ammonia followed by Huang-Minlon reduction.

Expedient synthesis of secondary amines bound to indole resin and cleavage of resin-bound urea, amide and sulfonamide under mild conditions

Abstract Highly efficient, new protocols for the attachment of primary amines to indole aldehyde resin using Ti(O i Pr) 4 –NaBH 4 and CH(OMe) 3 –NaBH 3 CN–HOAc are reported. Mild cleavage conditions for the release of urea, amide and sulfonamide products from the solid support using 1% trifluoroacetic acid (TFA) are developed.

Polymer-supported triacetoxyborohydride: a novel reagent of choice for reductive amination

A novel polymer-supported triacetoxyborohydride reagent for reductive amination of aldehydes and ketones is reported. The bound reagent was found to be shelf-stable and provided broad scope and reactivity in reductive amination reactions under mild reaction conditions. Streamlined protocols for its application in reductive amination reactions using both primary and secondary amines are described.

Selective Reduction of Dienones Synthesis of Intermediates for Sesqui-and Diterpenes

Abstract The tricyclic enones 15–20, intermediates to several sesqui-and diterpenes, have been synthesised in high yields involving selective hydrogenation of the disubstituted double bonds of the dienones 9-14 respectively in the presence of tris (triphenylphosphine)rhodium(I) chloride catalyst.

Stereocontrolled synthesis of xanthoperyl methyl ether

Abstract An efficient stereocontrolled route to xanthoperyl methyl ether ( 2 ) from 1,6-dimethoxynaphthalene ( 3 ) has been developed utilising reductive methylation of the tricyclic α,β-unsaturated ketone 10 in anhydrous ammonia as the key step.

Total synthesis of (±)-shonanyl methyl ether and (±)-ferruginyl methyl ether

Abstract An efficient reductive methylation of the tricyclic ketone 12 in anhydrous ammonia provided the β,γ-unsaturated ketone 15 in high yield which was subsequently converted into (±)-shonanyl methyl ether ( 3 ) and (±)-ferruginyl methyl ether ( 6 ).

Studies on metal-ammonia reduction and reductive methylation of naphthalenes

Abstract Reductive methylation of 1-carbomethoxy-4, 6-dimethoxynaphthalene in anhydrous ammonia gave 1-methyl-1-carbomethoxy-6-methoxy-1, 4-dihydronaphthalene in good yield. Metal ammonia reduction of the ketones 12 and 18 provided an expedient pathway for the synthesis of the α,β-unsaturated ketones 17 and 19 respectively.

Synthesis, reduction, and reductive alkylation of a few tricyclic α,β-unsaturated ketones

Abstract Reduction and reductive alkylation of the tricyclic α,β-unsaturated ketones 9–12 afforded the saturated ketones 13–21 in high yields.

An efficient total synthesis of (±)-isokhusimone

Abstract A total synthesis of (±)-isokhusimone 2 has been accomplished efficiently involving the rearrangement of the mesylate 17 as a key step. Ar 1 -5 cyclisation of the bromophenol 12 furnished the tricyclic dienone 13 which was subsequently converted into 17 .