M. M. V. Ramana

Urea Nitrate : A Reagent for Regioselective Nitration of Aromatic Amines

Abstract Nitration o f the aromatic amines with urea nitrate in sulphuric acid gave exclusively the p-isomer and when the p-position is blocked, the nitration occurred to give a m-nitroaniline derivative in excellent yields. However, nitration was not effected at o-position. Mechanistic aspect of this reaction is also discussed.

A new and convenient synthesis of 13,16-diazaestrone analogs

Abstract Imidazolidine-2,4-dione was chemoselectively N -alkylated at the imidic NH with several 2-(3,4-dihydro-1-naphthalenyl)ethyl-4-methylphenylsulphonates to give the corresponding imides for the first time which on selective reduction at one of the carbonyl groups followed by cyclization in PPA gave the corresponding title compounds.

Tandem acylation — cycloalkylation with cyclohexene l-acetic acid: A new entry to aporphine alkaloids

Abstract Tandem Acylation-Cycloalkylation of 3,4-dimethoxy phenylethylamine (1) with cyclohexene-1-acetic acid (2) in polyphosphoric acid (PPA) afforded 8-(2-aminoethyl)-1,2,3,4,4a,10a-hexahydro-9-oxo-phenanthrene (3) which on cyclisation followed by dehydrogenation with PdC afforded dehydronornuciferine (5) . Hydrogenation of 5 yielded (±) N-nornuciferine (6) .

Tandem Acylation - Cycloalkylation with Cyclohexene-1-Acetic Acid: A New Entry to Phenanthrene Alkaloids

Abstract Tandem acylation - cycloalkylation of 3,4 - dimethoxy-phenylethylamine (1) with cyclohexene -1-acetic acid (2) in polyphosphoric acid (PPA) afforded 8 - (2 - aminoethyl) - 1,2,3,4,4a,9,10,10a - octahydro - 9 - oxo - phenanthrene (3) which on dehydrogenation with Pd - C, followed by sequential N- methylation gave N- noratherosperminine (5) and atherosperminine (6) in good yields.

A Simple Approach to the Synthesis of Fluoren-9-Ones

Abstract Cyclohexene-l-Carboxylic acid (I) undergoes reaction with various aromatic substrates (2a-i) in presence of Polyphosphoric acid (PPA) at 100[ddot]c to give cis-1,2,3,4,4a,9a - hexahydrofluoren-9-ones (3a-i) in good yield. Dehydrogenation of (3a-i) with selenium powder afforded corresponding fluoren-9-ones (4a-i) in high yield.