Correlated rotation in a conformationally restricted amide

Dynamic two-dimensional 1H and 13C NMR studies of the conformationally restricted amide N-(1-naphthoyl)-cis-2,6-dimethylpiperidine reveal correlated rotation about the aryl–CO and amide bonds. The naphthalene and piperidine rings are tightly meshed and their rotation is virtually entirely (>99%) concerted, as evidenced by separate NMR measurement of the much slower rates of rotation about the individual aryl–CO and amide bonds. A disrotatory cogwheeling mechanism for the concerted rotation is proposed. Copyright © 2000 John Wiley & Sons, Ltd.