Shital K. Chattopadhyay

Combined claisen rearrangement and ring-closing metathesis as a route to oxepin- and oxocin-annulated coumarins

A new route involving a tandem Claisen rearrangement and ring-closing metathesis reaction has been developed for the synthesis of some hitherto unknown oxepin- and oxocin-annulated coumarin derivatives.

Enantiodivergent Synthetic Entry to the Quinolizidine Alkaloid Lasubine II

Intramolecular cycloaddition of the syn- and the anti-nitrone 9 and 13 leads stereoselectively to the azabicyclic compounds 10 and 14 which may provide access to both enantiomers of the quinolizidine alkaloid lasubine II.

Enantiodivergency and enantioconvergency in the synthesis of the dendrobate alkaloid 241D.

A diastereodivergent preparation of two N-alkenylnitrones (9 and 11) from easily available (R)-2,3-O-cyclohexylideneglyceraldehyde (5) led to an enantiodivergent synthesis of both enantiomers of the dendrobate alkaloid 241D in a sequential two-directional approach involving intramolecular nitrone cycloaddition as the key step. Either of these two nitrones could, in principle, be utilized for the preparation of the title compounds in an enantioconvergent fashion as well. The methodology was extended to prepare an analogue (33) of (-)-241D.

A new (3+3) annulation route to isoquinoline-3-carboxylates

A new synthesis of isoquinoline-3-carboxylates based on the palladium(0)-catalysed Heck-type arylation of 2-amidoacrylates with the appropriate 2-substituted iodobenzene is reported.

Combined Claisen rearrangement and olefin metathesis as a route to diverse naphthalene derivatives

Abstract A new route to several medium ring heterocycle and carbocycle fused naphthalene derivatives of potential medicinal importance has been developed involving tandem applications of Claisen rearrangement and ring‐closing diene metathesis as key steps.

Ag(I)-Catalyzed Domino Cyclization-Addition Sequence with Simultaneous Carbonyl and Alkyne Activation as a Route to 2,2'-Disubstituted Bisindolylarylmethanes.

An efficient synthesis of symmetrical 3, 3-bisindolylarylmethanes with various substituents on the indole moiety has been developed by Ag(I)-catalyzed cycloisomerization and an deoxygenative addition sequence on o-alkynylanilines and aryl aldehydes. Ag(I) is proposed to activate alkyne unit and carbonyl moiety simultaneously leading to a domino first 5-endo-dig indole annulation, addition to C═O, second indole annulation, and its dehydroxylative addition.

A unified approach to the important protein kinase inhibitor balanol and a proposed analogue.

Summary A common approach to the important protein kinase inhibitor (−)-balanol and an azepine-ring-modified balanol derivative has been developed using an efficient fragment coupling protocol which proceeded in good overall yield.

Studies on Amine Oxide Rearrangement: Synthesis of Pyrrolo[3,2‐c][1]benzothiopyran‐4‐one

Abstract A methodology, based on tandem [2,3] and [3,3] sigmatropic rearrangement, has been described for the synthesis of hitherto unreported, potentially bioactive pyrrolo[3,2‐c][1]benzothiopyran‐4‐ones (6a–g) derivatives.

δ,ε-Unsaturated α,β-diamino acids as building blocks for the asymmetric synthesis of diverse α,β-diamino acids.

A building block approach for the synthesis of α,β-diamino acids is described, which involves the diastereodivergent preparation of two sets of orthogonally protected δ,ε-unsaturated α,β-diamino acids as templates for the preparation of 12 new α,β-diamino acids of biological relevance using simple techniques.

Enantioselective synthesis of polyhydroxyindolizidinone and quinolizidinone derivatives from a common precursor

Summary A concise asymmetric synthetic route to two new tetrahydroxyindolizidinone and quinolizidinone derivatives has been developed from a common intermediate which featured a highly selective dihydroxylation reaction and a RCM reaction as key steps.