Studies in arylation of amino carbanions via benzyne intermediate and their applications in synthesis of alkaloids and related compounds

Abstract

The nucleophilic addition of amino-carbanions (derived from cyclic tertiary aralkyl amines) to arynes has been demonstrated to achieve arylation in a one-pot procedure. The developed protocol has been employed in the synthesis of a variety of alkaloids and related compounds. Chapter 1 is about the general introduction to aryne chemistry and heteroatom mediated lithiations. The role of arynes and lithiated intermediates in heterocycle synthesis has been discussed. Moreover, the concepts of lithiation regioselectivity has been described briefly. Chapter 2 describes the results of nucleophilic addition of and#945;-amino carbanions derived from Lewis-acid complexed tetrahydroisoquinolines to arynes to afford 1-aryl-Nmethyl-1,2,3,4-tetrahydroisoquinolines. Moreover, the application of the present protocol for the synthesis of all three alkaloids of Cryptostylis fulva i.e. Cryptostyline I-III is discussed. Chapter 3 is sub-divided into two parts. Part A includes the results of nucleophilic addition of and#946;-amino carbanions of tetrahydroisoquinolines to arynes to afford 4-aryl-N-methyl-1,2,3,4-tetrahydroisoquinolines. Its utility in the synthesis of Cherylline dimethyl ether, Latifine alkaloid and medicinally important molecule i.e. Nomifensine has been described. Chapter 3 is sub-divided into two parts. Part A includes the results of nucleophilic addition of and#946;-amino carbanions of tetrahydroisoquinolines to arynes to afford 4-aryl-N-methyl-1,2,3,4-tetrahydroisoquinolines. Its utility in the synthesis of Cherylline dimethyl ether, Latifine alkaloid and medicinally important molecule i.e. Nomifensine has been described. newline