Conformational analysis of conjugated polyenes by nuclear magnetic resonance and low resolution microwave spectroscopy

Abstract

Steinmetz et al.Professor W. J. Taylor stimulated to some degree our discussion on comparison of correlation and ordering. References and Notes

A Model Study of Fecapentaenes: Mutagens of Bacterial Origin with Alkylating Properties

“…2) with the use of (methoxymethyl)trimethylsilane (8) (12,13) [similar to the procedure used to synthesize 1 (14)]. The aldehydes 9c, 9d, and 9e were prepared (15,16), and 9a and 9b were purified, commercial products (17).…”

Structure and Conformational Dynamics of Trichothecene Mycotoxins

“…The magnitude of the coupling constant demonstrates an anti conformation between H-8′ and H-9′. Large values, i.e., 3 J > 10.7 Hz, were observed in a study of conjugated polyene aldehydes and ketones where rotational constants derived from their microwave spectra clearly demonstrated an extended conformation . With roridin A, the hybridization of C-6′ is sp 3 instead of sp 2 and the scope of the conjugated system is reduced with a resulting increase in flexibility around C-6′.…”

“…Large values, i.e., 3 J > 10.7 Hz, were observed in a study of conjugated polyene aldehydes and ketones where rotational constants derived from their microwave spectra clearly demonstrated an extended conformation. 23 With roridin A, the hybridization of C-6′ is sp 3 instead of sp 2 and the scope of the conjugated system is reduced with a resulting increase in flexibility around C-6′. The section where conjugation is preserved maintains an anti, extended conformation, as shown by the value of 3 J 8′H,9′H , 11.5 Hz.…”