Uncatalyzed reaction of silyl ketene acetals with oxalyl chloride: a straightforward preparation of symmetrical pulvinic acids.
[reaction: see text] Several natural pulvinic acids were synthesized. Silyl ketene acetals derived from methyl arylacetates (4 equiv) reacted with oxalyl chloride at -78 degrees C, without the need of adding a catalyst. After treatment of the crude diketones with DBU and acidification with hydrochloric acid, symmetrical pulvinic acids methyl esters were obtained. Saponification of the methyl esters afforded the corresponding pulvinic acids in 60-70% overall yields from oxalyl chloride.
Heurtaux
Benoît
B
CEA-Saclay, Service de Marquage Moléculaire et de Chimie Bioorganique, Bât. 547, 91191 Gif-sur-Yvette, France.
Lion
Claude
C
Le Gall
Thierry
T
Mioskowski
Charles
C
D000080:Acetals / Q000737:chemistry*; D002264:Carboxylic Acids / Q000138:chemical synthesis* / Q000737:chemistry; D002384:Catalysis; D002712:Chlorides / Q000737:chemistry*; D005030:Ethylenes / Q000737:chemistry*; D007536:Isomerism; D007659:Ketones / Q000737:chemistry*; D007783:Lactones / Q000138:chemical synthesis* / Q000737:chemistry; D008745:Methylation; D015394:Molecular Structure; D010070:Oxalates / Q000737:chemistry*
D000080:Acetals; D002264:Carboxylic Acids; D002712:Chlorides; D005030:Ethylenes; D007659:Ketones; D007783:Lactones; D010070:Oxalates; C008223:ketene; C492654:pulvinic acid; C092266:oxalyl chloride