REACTION OF DIMETHYL SODIO-3-KETOGLUTARATE WITH GLYOXAL AND SUBSTITUTED GLYOXALS; FIRST EXPEDITIOUS PREPARATION OF BICYCLOOCTANE-3,7-DIONE; SYNTHESIS AND CRYSTAL STRUCTURE OF 5,7-DIHYDROXY-4-METHOXYCARBONYL-3-PHENYL-1-INDANONE

Article abstract of DOI:10.1016/0040-4020(82)85046-1

A simple and efficient two-step preparation of bicyclo<3.3.0>octane-3,7-dione starting from the sodium enolate of dimethyl 3-ketoglutarate and glyoxal is described.This is an unprecedented case in which a condensation reaction of glyoxal is more successful under vigorous conditions (refluxing methanol) than under much milder ones (buffered water at ambient temperature).The major product (after hydrolysis-decarboxylation) from the analogous sequence with phenylglyoxal is 5,7-dihydroxy-4-methoxycarbonyl-3-phenyl-1-indanone, the result of a Dieckmann reaction in addition to the Michael and aldol reactions.Only the latter two occur in aqueous buffers, where the product after hydrolysis-decarboxylation is 1-phenylbicyclo<3.3.0>octane-3,7-dione.The X-ray crystal structure of the indanone reveals a novel hydrogen bonding phenomenon.