Tandem intramolecular Michael addition/aldol condensation or acylation applied to D-glucose-derived substrates: preparation of enantiomeric octahydronaphthalenone derivatives equipped with C- and O-functionalities
作者:Kinichi Tadano、Kensuke Nagashima、Yoshihide Ueno、Seiichiro Ogawa
DOI:10.1021/jo00042a034
日期:1992.7
An enantiomerically pure (1,2-isopropylidenedioxy)tetrahydrofuran derivative, 9, bearing acetonyl and propionaldehyde side chains smoothly underwent aldol cyclization under basic conditions. The major product was the cis-aldol 21S, accompanied by the trans-diastereomer 21R in a ratio of 4 to 1. Further functionalized substrates 10 and 11, with either a (4-acetyl)- or a (4-ethoxycarbonyl)-3(E)-butenyl group, smoothly underwent a tandem Michael addition/aldol condensation or acylation by treatment with sodium hydride (NaH). In the case of 10, two cis-fused octahydronaphthalenones, 23 and 25, and a trans-fused diasteromer, 24, were isolated in 20%, 33%, and 11% yields, respectively. The substrate 11 provided a cis-substituted perhydrobenzofuran derivative, 26, and cis- and trans-fused octahydronaphthalenediones, 27 and 28, in 52%, 17%, and 9% yields, respectively. An intramolecular S(N)2' type cyclization of the corresponding 5-chloro-3(E)-pentenyl derivative, 14, provided exclusively (96%) the perhydrobenzofuran derivative, 29, in which the two newly introduced substituents are disposed in a cis relationship. The stereochemical assignments for each cyclization product were achieved by H-1 NMR analysis of the cyclization products or their chemically modified compounds. Preferential formation of the cis-fused carbocycles in the present studies is rationalized from a stereoelectronic viewpoint. Furthermore, the effect of substituents on the cyclization was investigated using two tetrahydrofuran derivatives, 20S and 20R. Base treatment of 20S gave the cis-fused tandem cyclization product 30 and the trans diastereomer 31 in a ratio of 3.8 to 1. In contrast, 20R gave two cyclization products, 32 and 33, in a ratio of 5 to 1, as a result of a preferential trans cyclization mode.