Structural Studies of 1,8‐Disubstituted Naphthalenes as Probes for nucleophile‐electrophile interactions

Abstract

Abstract Results of crystal structure analyses of seven 1, 8‐disubstituted naphthalenes ( 2a , 8‐( N,N ‐dimethylamino)‐1‐naphthyl methyl ketone; 2b , 8‐( N, N ‐dimethylamino)naphthalene‐1‐carboxylic acid; 2c , methyl 8‐( N, N ‐dimethylamino)naphthalene‐1‐carboxylate; 2d , 8‐methoxy‐1‐naphthyl methyl ketone; 2e , 8‐methoxynaphthalene‐1‐carboxylic acid; 2f , N, N ‐dimethyl‐8‐methoxynaphthalene 1‐carboxamide; 2g , N, N ‐dimethyl‐8‐hydroxynaphthalene‐1‐carboxamide) with a nucleophilic centre (N(CH 3 ) 2 , OCH 3 , OH) at one of the peri positions and an electrophilic centre (carbonyl C) at the other are described. All seven molecules show a characteristic distortion pattern: the exocyclic bond to the electrophilic centre is splayed outward, and the one to the nucleophilic centre is splayed inward; the carbonyl C is displaced from the plane of its three bonded atoms towards the nucleophile. This distortion pattern differs from that found in other 1,8‐disubstituted naphthalenes and is interpreted as an expression of incipient nucleophilic addition to a carbonyl group. The crystal structure of 2b contains an ordered arrangement of equal numbers of amino acid and zwitterionic molecules.