A Novel Synthesis of Functionalized Tetrahydrofurans by an Oxa-Michael/Michael Cyclization of γ-Hydroxyenones

Abstract

An approach to highly functionalized tetrahydrofuran derivatives based upon a novel Oxa-Michael/Michael dimerization of cis-gamma-hydroxyenones is presented. The reaction begins with either 1,2-dioxines or trans-gamma-hydroxyenones and proceeds by addition of one molecule of trans-gamma-hydroxyenone to another molecule of cis- or trans-gamma-hydroxyenone catalyzed by an alkoxide or hydroxide base. Subsequent intramolecular Michael addition of the keto-enolate gives the observed tetrahydrofurans. Substitution at both the 2- and 4-positions of the gamma-hydroxyenone is tolerated; however, for 4-substituted gamma-hydroxyenones, selectivity issues arise due to the possibility of heterochiral or homochiral dimerizations. The major products were those with all contiguous groups trans.

1,4-Diphenylbutane-1,4-dione

“…E64, o2423 [doi:10.1107/S1600536808038798] 1,4-Diphenylbutane-1,4-dione Zhigang Wang S1. Comment 1,4-Dicarbonyl compounds constitute key intermediates in various natural product syntheses, and they are important synthetic precursors of cyclopentenones, cyclopenta-1,3-diones, butenolides, and derivatives of furan and pyrrole (Chiu & Sammes, 1990;Greatrex et al, 2003;Nagarajan & Shechter, 1984). Herewith we present the title compound (I) (Fig.…”

Rearrangements of organic peroxides and related processes

“…Finally, the protonation of the tert -butoxide anion results in the formation of tert -butanol ( 228 ). As alternative bases Et 3 N [ 338 – 339 ], phosphorus ylides [ 340 ] and LiOH [ 341 – 342 ] can be used and the Kornblum–DeLaMare rearrangement proceeds also on SiO 2 [ 343 ].…”

Total Synthesis of (−)-Angiopterlactone B

“…Zou and co-workers noted that (+)-angiopterlactone B ( 1 ) may be derived from the coisolated (−)-angiopterlactone A ( 2 ) by an intramolecular Michael reaction (Scheme ). With no further biosynthetic speculation provided, we ventured that (−)-angiopterlactone A ( 2 ) might be formed by an intermolecular oxa-Michael reaction between γ-lactone 3 and δ-lactone 4 . This proposal was driven by the recognition that lactones 3 and 4 are isomers of one another.…”