Stereoselective sodium borohydride reductions of cyclopentanones: influence of ceric chloride on the stereochemistry of reaction

Abstract

Recebido em 22/8/97; aceito em 23/1/98In this paper we describe the reduction by NaBH 4 of some cyclopentanones containing an oxygenated function at the side chain position β β β β β to the carbonyl group, both in the presence and in the absence of CeCl 3 . Some suggestions for the rationalization of the results are discussed, considering the stereochemical course of the reactions.

Long‐range JCH heteronuclear coupling constants in cyclopentane derivatives

“…1) were first prepared from isophorone in our laboratory for synthetic studies purposes, 5,6 as shown in Scheme 1.…”

“…Cyclopentane derivatives are important intermediates in organic synthesis; 5,6 the determination of the structure and relative stereochemistry of these compounds is frequently a difficult task. In previous studies, we have shown that the long-range homonuclear spin-spin coupling constant cannot be reduced to the simple rule of planar W conformation.…”

Detailed assignments of 1H and 13C NMR spectral data of 14 cyclopentane derivatives

“…1,2 For the measurements reported in this paper they were prepared as previously described, and then purified (mainly by column chromatography) until clean spectra were obtained. For the assignment of the 1 H and 13 C NMR spectra of 1-8, a combination of two-dimensional J-resolved and HMQC experiments were carried out.…”

Stereochemistry of cyclopentane derivatives from 2, 3JCH dependence on dihedral angle (θ HCCX)

“…[1,2] However, the determination of the structure and the relative stereochemistry of these compounds is frequently a difficult task, due to the various conformers that these compounds can exhibit.…”