219616-86-1Relevant academic research and scientific papers
Enolic ortho esters. VIII. Synthesis of (2S,3S)-2,3-bis(methoxymethyl)-1,4,6-trioxaspiro[4.5]dec-7-ene
Collins, David J.,Crosby, Ian T.
, p. 1025 - 1030 (2007/10/03)
Enolic ortho ester (2S,3S)-2,3-bis(methoxymethyl)-1,4,6-trioxaspiro[4.5]dec-7-ene (10b) was synthesized in 65% yield by cycloadditon of acrolein with the ketene acetal (4S,5S)-4,5-bis(methoxymethyl)-2methylidene-1,3-dioxolan (7), derived by potassium t-butoxide treatment of (4S,5S)-4,5-bis(methoxymethyl)-1,3-dioxolan (4). Lewis acid catalysed reaction (TiCl4, CH2Cl2, -78°) of the enolic ortho ester (10b) with the ketene silyl acetal 3-phenylmethyl-2-trimethylsilyloxy-4,5-dihydrofuran (15) afforded the formyl keto ester 3-[4′,5′-bis(methoxymethyl)-2′-(4″-oxobutyl)-1′, 3′-dioxolan-2′-yl]-3-phenylmethyl-4,5-dihydrofuran-2(3H)-one (16) (39%) with only poor diastereoselectivity. Attempts to make the bis(phenylmethyl) analogue (10a) of enolic ortho ester (10b) were thwarted by the finding that the required ketene acetal (9), analogous to (7), could not be generated by elimination from (4S,5S)-2-bromomethyl-4,5-bis(phenylmethyl)-1,3-dioxolan (6), or from the derived phenyl selenoxide (8), under a variety of conditions.
