The Behavior of Certain Coumarins and Furocoumarins Toward Sulfur Reagents

The behavior of 4-hydroxycoumarin (1), 7-hydroxycoumarin (2), 4-hydroxy-bergapten (3), and 4-hydroxyisopimpinellin (4) toward sulfur reagents, namely, thionyl chloride, phosphorus pentasulfide, thiolacetic acid, and Lawesson's reagent (5), was studied. The nature of products in each case depended upon the type of reactants and reaction conditions. Possible reaction mechanisms were considered, and structural elucidations of the new products were based upon compatible elementary and spectroscopic evidences.     

New Polymers Derived from Poly(Methylphenylphosphazene)

Abstract

The sequential treatment of [Me(Ph)PN]_n with n-BuLi and electrophiles such as substituted chlorosilanes, aldehydes and ketones, and carbon dioxide results in new functionalized polyphosphazenes. Graft copolymers have also been prepared by using the anionic polymer intermediate to initiate anionic addition polymerization of styrene, CH₂=C(Ph)H, and ring opening polymerization of hexamethylcyclotrisiloxane, [Me₂SiO]₃.     

Microwave-Assisted Syntheses of 2-Phenylbenzothiazoles

A new and easy synthetic route to 2-phenylbenzothiazoles has been achieved by direct thiation of benzoyl derivatives of aniline, various substituted anilines, and 1-naphthylamine under microwave irradiation. The oxidative cyclization using elemental sulfur in the presence of a catalytic amount of iodine is inexpensive and worked well for a number of anilides.     

Synthesis of New Quinoxaline Derivatives

New quinoxaline derivatives were prepared by the reaction of 2-hydroxyquinoxaline 1 and alkyl or alkylaminoalkyl halides in dimethylformamide using potassium carbonate as a base. The hydroxyl group was readily converted into a thiol function by treatment with phosphorus pentasulfide and/or Lawesson's reagent in pyridine, and the subsequent alkylation of the thiol group was carried out under phase-transfer catalyst conditions. Chlorination of 1 was carried out with phosphorus oxychloride. Branching of alkylamino side chains to the 2-OH, 2-SH, and 2-Cl quinoxalines resulted in the synthesis of several compounds. Synthesis and alkylation of 2-hydroxy 7-nitroquinoxaline are also reported.