Isopropylidenation of sugar osazones

ABSTRACT

Acetonation of D-erythro- and L-erythro- pentose phenylosazone afforded the respective alpha-terminal isopropylidene derivatives 2 and 6 respectively. Their acetylation gave the corresponding 3-O-acetyl-4, 5-O-isopropylidene derivatives 3 and 7, respectively. Benzoylation of 2 afford the dibenzoyl derivative, 3-O-benzoyl-4, 5-0-isopropylidene-D-erythro-N-benzoyl-pentose phenylosazone [4]. Acetonation of D-threo-pentose phenylosazone [8] gave two products of the alpha-terminal and alpha-thre isopropylidene derivatives 9 and 10, respectively. Acetylalion of 10 and benzoylation of 9 gave the respective monoacetyl, and dibenzoyl derivatives 12 and 11, respectively. Acetonation of D-arabino-hexose phenylosazo-ne [13] afforded the mono- and di-isopropylidene derivatives 14 and 15 reapectively. Acetylation of 14 gave 3, 4-di-O-acetyl derivative 18. Isopropylidenation of D-lyxo-hexose phenylosazone [17] afforded the monoisopropylidene 18, which gave -upon acetylation the corresponding 3, 4-di-O-acetyl derivative 19