and the use of tin (IV) chloride, capable of a 1,4-chelation, seem to impose their influence in the regiospecificringopening of 1a-g. The conformational analyses carried out on 2b and (1R,3R)-2e and (1R,3S)-2e clearly indicate that the N1(sp2)-C1-C2-C3 moiety tends to fold in a gauche conformation. The antitumour activities of compounds 2b-g were assessed against HEp human cells showing that 2c is 4-fold
A New Systematization of the Conformational Behavior of Seven-Membered Rings. Isoclinal Anomeric and Related Orientations<sup>1</sup>
作者:A. Entrena、J. Campos、J. A. Gómez、M. A. Gallo、A. Espinosa
DOI:10.1021/jo951950j
日期:1997.1.1
The chair and twist-chair conformations of seven-memberedrings are classified as a function of the signs of their endocyclic torsion angles. The conformational analysis (MM3) of the methoxy- and methyloxepanes 1-6 used as patterns allows the study and classification of the different types of hydrogen orientation in the seven-membered saturated heterocycles. General principles are established, allowing