ChemInform Abstract: O‐ UND C‐ELEMENTORGANISCHE ISOMERE 15. MITT. ACYLIERUNG O‐SILYLSUBSTITUIERTER KETENACETALE

Abstract

Durch Behandlung des Bromacetaldehyddiäthylacetals (I) mit festem KOH entsteht das Ketenacetal (II).

Acetyl Chloride

“…The third possible isomer (trans-β-siloxycrotonate) is accessible either by silylation of the acetoacetic ester (TMSCl, Et 3 N, THF, ) 139 or by HgBr 2 /Et 3 SiBr-catalyzed equilibration of the cis isomer. 137 The silyl ketene acetal strategy can also be used to effect γacetylation of α,β-unsaturated esters (AcCl/cat. ZnBr 2 , CH 2 Cl 2 , rt) 140 and β-ketoesters (AcCl, Et 2 O, −78 • C).…”