P. B. Sattur

An Efficient Synthesis of 3,4-Dihydro-4-Imino-2(1H)-Quinazolinones

Abstract A new one-pot convenient preparation of 3,4-dihydro-4-imino-2(1H)-quinazolinones (4) is described by the reaction of 2-aminobenzonitriles (1) with chlorosulfonyl isocyanate (2), while the reaction of 1 with chlorocarbonyl isocyanate (6) affords ureidobenzonitriles (7), which on thermal cyclization gives 4.

A New Route to 4-Phenyl-2(1H) Quinazolinones; Reactions of 2-Amino Benzophenones with Chlorosulfonyl Isocyanate

Abstract We have been interested in the synthesis of substituted quinazolinones as a part of our continuing research programme in search of potent physiologically active molecules. The present communication explores further synthetic uses of chlorosulfonyl isocyanate (CSI), a reagent developed by Graf1,2 and extensively employed in the preparation of a wide variety of heterocyclic systems as well in various synthetic conversions3.

Enzymatic cyclization of 2-(carbamoyloxy)benzoates, 2-(sulfamoyloxy)benzoates and 2-(carbamoyloxy)benzophenones with yeast and lipase

The cyclization of labile functionalized 2-(carbamoyloxy)-benzoates, 2-(sulfamoyloxy)benzoates and 2-(carbamoyloxy)benzophenones to 1,3-benzoxazine-2,4-diones, 4-oxo-3,4-dihydro-1,2,3-benzoxathiazine 2,2-dioxides and 4-phenyl-1,3-benzoxazin-2-ones with yeast as well as lipase is described. This approach establishes the application of enzymes for gram scale cyclization of such substrates under mild conditions

Reactions with Chlorosulfonyl Isocyanate: Formation of 2H-1,3-Benzoxazine-2-Ones

Abstract In recent years chlorosulfonyl isocynate (CSI), an electrophilic reagent has been extensively employed in the synthesis of heterocyclic compounds. We have earlier reported on the reactions of CSI with - 2- aminobenzophenones leading to the formation of 4-aryl-2(IH)-quinazolinones1 and with 2-hydroxy benzaldehydes, 2-hydroxyacetophenones or -benzophenones at elevated temperature, 2-hydroxyacetophenones or-benzophenones or- benzophenones at elevated temperature (100–105°) giving rise to 1,2,3- benzoxathiazine- 2, 2-dioxides2. It is known that the temperature profoundly influences the course of the reaction and formation of the products in case of phenolic compounds, it was considered of interest to carry out the reaction of CSI with 2-hydroxycompounds (1a-e;6a-e) at room temperature (25–30°), to obtain 1,3-benzoxazine-20-ones which have attracted considerable attention to thier biological activity.

Catalase-mediated cyclization: Synthesis of 3-allyl-4-imino substituted 2(1H)-quinazolinones and 1,3-benzoxazine-2(3H)-ones

Abstract The cyclization of N-allyl carbamoyl anthranilonitriles as well as O-allylcarbamoyl salicylonitrile to 2(1H)-quinazolinones and 1,3-benzoxazine-2(3H)-ones in quantitative yields by employing catalase has been described.

Enzymatic cyclization of 2-carbamoyloxy benzoates: Formation of 2H-1,3-benzoxazine-2,4(3H)-diones

Abstract The cyclization of 2-carbamoyloxy benzoates to 1,3-benzoxazine-2,4-diones in high yields by rat liver microsomal fractions has been investigated.