Studies on the bridgehead and bridged hetero annulenes

Abstract

Annulene chemistry, one of the most important parts of Organic chemistry both from theoretical and practical point of view, play a key role in the studies of aromaticity in various bridged and heterobridge orga-nic compounds. The synthesis of 1,6-methano[10]annulene and their mono and disubstituted derivatives by using newer reagents comprise the subject of the present thesis. At the same time attempt has been made to study the addition and cycloaddition reactions of 1,3,5-cyclohepta-1,6-dicarboxa-mide with carbondisulphide and various derivatives of dichlorophosphoro-chloridate and thiophosphorochlorioate respectively. The results of these investigation are presented in six chapters comprising the Part-I. A brief introductory note is also given at the beginning of these chapters. In Part-II, the cycloaddition reactions of substituted hydrazones has been discussed. In the introductory note a brief review of the historical develop-ment and published literature on [10],[12],[14],[16],[18],[20] and [22]annulene system are given. PART - I CHAPTER ONE SYNTHESIS OF THE KEY INTERMEDIATE (Scheme 1) 1.1 Synthesis of monoacetyl cyclohepta-1,3,5-triene (II) : This chapter commence with the synthesis of monoacetyl cyclohepta 1,3,5-triene from the starting material cyclohepta-1,3,5-triene (I) using weak Lewis acid (ZnCl2) as catalyst for the Friedel-Crafts acylation reaction. 1.2 Synthesis of 1,6-diacetyl cyclohepta-1,3,5-triene (III) : This diacetylated liquid compound (III) was prepared by the same F. C. reaction under controlled condition using strong Lewis acid (AlCl3) as catalyst and the monoacetyl derivative (II) as the starting material. 1.3 Synthesis of cyclohepta-1,3,5-triene-1,6-dicarboxylic acid (IV) : The diacetyl cyclohepta-1,3,5-triene (III) upon haloform reaction under controlled condition, yielded the solid title dicarboxylic acid (IV). 1.4 Synthesis of cyclohepta-1,3,5-triene-1,6-diacid dichloride (V) : The title compound (V) was prepared from the above dicarboxylic acid (IV) by simple chlorination of the...