Durga Nath Dhar

Reaction of chlorosulfonyl isocyanate with nitrones: an efficient method for the synthesis of cyclic enamides and 2H-pyrroles

Abstract Reaction of chlorosulfonyl isocyanate (CSI) with nitrones (derived from cyclic conjugated ketones), 1 - 7 and 3,4-dihydro-2H-pyrrole-1-oxides, 15a - f ,-has been studied. Nitrones, 1 - 7 , react with CSI to form the enamidea, 8 , 10 - 14 , and the cyclil-amide, 9 , in yields ranging from 33 to 72 %. However, the 5,4-dihydro-2H-pyrrole-1-oxides, 15a - e , on reaction with CSI gave the 2H-pyrr-oles, 16a - e , in good yields. The 3,4-dihydro-2H-pyrrole-1-oxide, 15f , under similar experimental conditions gave the pyrrolidone, 17f , in 40% yield. Plausible mechanisms for the above mentioned rearrangement and conversions have been proposed with experimental evidences.

Synthesis of spiro-pyrazolines: reaction of 1,3-diphenylnitrilimine with fulvenes

Abstract A one-step synthesis of a new series of spiro-pyrazolines has been accomplished by the 1,3-dipolar cycloaddition of 1,3-diphenylnitrilimine with various fulvenes (2,3,4,5-tetraphenyl fulvene (1) and its analogues (2, 3), 9-benzalfluorene (7) and its analogues (8, 9) and 6,6-diphenylfluvene (13)). With the exception of 13 all other fulvenes undergo 1,3-dipolar cycloaddition across the exocyclic double bond to give the hitherto unreported spiro-pyrazoline derivatives (1-6, 10-12). In the case of 13, however, the addition of 1,3-dipole takes place at the site of endo-cyclic double bond, leading to the formation of a pyrazoline derivative (14).

A Conveient One-Pot Synthesis of 1,3-Dioxolan-2-Ones from Epoxides Using Chlorosulfonyl Isocyanate

Abstract An efficient, simple and stereospeciric one-pot method is described for the conversion of epoxides to 1,3-dioxolan-Z-ones, by using chlorosulfonyl isocyanate (CSI).

REACTIONS OF CHLOROSULFONYL ISOCYANATE WITH THIAZOLINES AND OXAZOLINES : FORMATION OF THIAZOLO AND OXAZOLOTHIADIAZINES

Abstract 2-Alkylthiazolines and oxazolines undergo cyclization reaction with chlorosulfonyl isocyanate to give thiazole and oxazole fused thiadiazine derivatives.

Rearrangement of nitrones to amides using chlor0sulfonyl isocyanate

Abstract Reaction of chlorosulfonyl isocyanate (CSI) with nitrones 1 a-n and 5 a,b has been studied. α, α, N-Triaryl nitrones 1 a-n react with CSI to form the N,N-diaryl arylamides 3 a-n and 4 i-n in good yields. In the case of α-H, α, N-diaryl nitrones 5 a,b however, two compounds viz., the rearranged product 11 a,b and the 1,4-dihydro tetrazines 10 a,b are formed. The effect of substituents on the rearrangement has been studied. It is found that the nature of the substituent has got a profound effect on the rearrangement. We have also noted that the rearrangement is independent of the syn or anti configurations of the nitrones.

A FACILE SYNTHESIS OF TRIAZOCINONES AND OXADIAZOCINONES

Abstract A facile synthesis of 4,7-diaryl-1,3,6-trihydro-1,3,6-triazocin-2-ones and 5,8-diaryl-3,6-dihydro-1,3,6-oxadiazocin-2-ones is reported by the interaction of cholorosulfonyl and 2H-azirines.

A Simple Route for the synthesis of Oxazepine-2-One Systems using Chlorosulfonyl Isocyanate

Abstract Reaction between the 1-aroyl-2-arylcyclopropane (cyclopropyl chalcone) with chlorosulfonyl isocyanate leads to the formation of seven membered heterocyclic product, namely, oxazepine-2-one.

Cycloaddition of Chlorosulfonyl Isocyanate to 2H-Azirines: Formation of [2+2+2] Cycloadducts

Abstract Chlorosulfonyl isocyanata (CSI) reacts with 2H-azirines 1 a-c at -78°C to form [2+2+2] cycloadducts 3a-c and 4a-c. The tricyclic aziridine derivatives 4a-c undergo CSI extrusion reactions and subsequent oxidation to the corresponding pyrazines 5a-c. Structural identifications of 3a-c and 4a-c are based on ir, nmr and mass spectral data.

Cyclization of 2′-Aminochalcones with Chlorosulfonyl Isocyanate

Abstract Cyclization of 2′-aminochalcones 1a-e with chlorosulfonyl isocyanate (CSI), at low temperature, afforded 2(1H)-quinazolinone 2a-e and 1H-2,1,3-benzothiadiazine 2,2-dioxide 3a-e derivatives.

Cycloaddition of chlorosulfonyl isocyanate with arylmethylenemalonaldehydes

Abstract The reaction of chlorosulfonyl isocyanate with arylmethylenemalonaldehydes afforded the fused 1,3-oxazin-2-one derivatives.