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

Abstract

Results of crystal structure analyses of seven 1,ELdisubstituted naphthalenes -8-hydroxynaphthalene-1-carboxamide) with a nucleophilic centre (N(CH3)2, OCH3, 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,s-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. I) 2, 3,

peri-Interactions in Naphthalenes, 14 [1]. Pyramidalization versus Planarization at Nitrogen in 8-Dialkylamino-naphth-1-yl Compounds as a Measure of peri Bond Formation

“…The ylidic formula explains the entirely different chemical properties of the stable DAN-Si compounds and the corresponding 8-MeO-C 10 H 6 -Si compounds which are indeed arylsubstituted silenes because of the poor σ -donicity of MeO and hence unstable. The differences of chemical behaviour contrast with the uniformity shown by the 8-Me 2 N-/MeO-C 10 H 6 -CO-R compounds [42,43] in which N/O→C interactions play no significant role [5] (vide supra). The length of the Si-C bond, 175 -176 pm, and the planarity at the ylidic C atom have their counterparts in phosphonium ylids where the ylidic C atom likewise tends to be planar and the P + -C − bond is shorter than other P + -C single bonds [68].…”

“…Schweizer et al [42] and Clayden et al [43] studied potential N→C interactions in DAN-C(=O)R compounds (R = Me, OH, OMe, NR' 2 ). Deviations of the -C(=O)R substituent from planarity and the windshield wiper phenomenon [2,5] of the bay angles of the C 10 skeleton induced Schweizer et al [42] to regard the structures as frozen early stages on the reaction coordinate of nucleophilic addition of the amine to the carbonyl function.…”

“…Deviations of the -C(=O)R substituent from planarity and the windshield wiper phenomenon [2,5] of the bay angles of the C 10 skeleton induced Schweizer et al [42] to regard the structures as frozen early stages on the reaction coordinate of nucleophilic addition of the amine to the carbonyl function. Several objections may be raised.…”

1,8-Dibenzoyl-2,7-dimethylnaphthalene

“…ORTEP (Johnson, 1965) References: (a) Cruickshank (1957). (b) Schweizer, Procter, Kaftory & Dunitz (1978). (c) White, Carnduff, Guy & Bovill (1977b).…”

Structural studies of peri-interactions and bond formation between electron-rich atomic centres and N-phenylcarboxamides or nitroalkenyl groups

“…We may add that structures for comparison should be measured at low and similar temperatures to minimize the effects of thermal motion on the derived structural geometries. Indeed, some of the structures measured in the original pioneering work 4 should now be remeasured to put the data in Table 1 on a more closely comparable basis. Lloyd-Jones has reported interesting initial investigations of estimating distances between peri-substituents using 15 N, 15 N coupling constants across hydrogen bonded amino groups, but correlation of calculated coupling constants with N,N separation was better than for the observed data.…”