Intramolecular aldol cyclization of L-lyxo-hexos-5-ulose derivatives: a new diastereoselective synthesis of D-chiro-inositol.
The DBU-promoted intramolecular aldol condensation of two partially protected L-lyxo-hexos-5-ulose derivatives (8 and 9), in turn obtained starting from methyl beta-D-galactopyranoside, takes place with fairly good yield and complete diastereoselectivity to give 2L-(2,3,6/4,5)-pentahydroxycyclohexanone derivatives, 10 and 11. The stereoselective reduction of inosose 10 with sodium triacetoxyborohydride leads, after catalytic debenzylation, to D-chiro-inositol (1), while the sodium borohydride reduction furnishes, with opposite stereoselectivity, a derivative of allo-inositol.
Catelani
Giorgio
G
Dipartimento di Chimica Bioorganica e Biofarmacia, Università degli Studi di Pisa, Via Bonanno, 33, I-56126 Pisa, Italy. giocate@farm.unipi.it
Corsaro
Antonino
A
D'Andrea
Felicia
F
Mariani
Manuela
M
Pistarà
Venerando
V
D003500:Cyclization; D007294:Inositol / Q000031:analogs & derivatives* / Q000138:chemical synthesis* / Q000737:chemistry; D008358:Mannose / Q000031:analogs & derivatives* / Q000737:chemistry; D008756:Methylgalactosides / Q000737:chemistry; D013237:Stereoisomerism
C448621:5-ketomannose; D008756:Methylgalactosides; C002183:inosose; D007294:Inositol; D008358:Mannose