Total synthesis of the AB disaccharide unit of olivomycin A
作者:William R Roush、Julie A Straub
DOI:10.1016/s0040-4039(00)84793-0
日期:1986.1
An efficient (10 step, 17% overall yield), highly diasteroselective totalsynthesis of disaccharide , corresponding to the AB disaccharide unit of olivomycin A, is described.
Indium-mediated allylation of aldehydes: A convenient route to 2-deoxy and 2,6-dideoxy carbohydrates
作者:Wolfgang H. Binder、Reinhard H. Prenner、Walther Schmid
DOI:10.1016/s0040-4020(01)80790-0
日期:1994.1
The allylation of protected polyhydroxy aldehydes 1 and 14 has been achieved by indium metal with ultrasound promotion generating the diastereomeric pair of homoallylic polyols 3, 4 and 16, 17 respectively with moderate to good stereoselectivity. Pursuing this allylation strategy with the corresponding deprotected polyhydroxy aldehydes led to the same pair of homoallylic polyols but with a quite different ratio of the diastereomers generated. The polyols were further transformed to 2-deoxy (5 and 6) and 2,6-dideoxy (18 and 19) carbohydrates by ozonolysis.
ROUSH, WILLIAM R.;LIN, XIAOFA;STRAUB, JULIE A., J. ORG. CHEM., 56,(1991) N, C. 1649-1655
作者:ROUSH, WILLIAM R.、LIN, XIAOFA、STRAUB, JULIE A.
DOI:——
日期:——
A highly stereoselective synthesis of the AB disaccharide unit of olivomycin A
作者:William R. Roush、Xiaofa Lin、Julie A. Straub
DOI:10.1021/jo00004a054
日期:1991.2
A highly stereoselective synthesis of the AB disaccharide (4c) of olivomycin A is described. The synthesis features the double asymmetric allylboration of alpha,beta-dialkoxy aldehyde 8 using tartrate allylboronate (S,S)-9, which provides triol derivative 10 with the correct relative and absolute stereochemistry for utilization in syntheses of the A and B monosaccharides. The derived diol benzyl ether 11 was converted into 3-hydroxy-2-deoxy-lyxo-pyranoside 16 and thioglycoside 18 via the intermediacy of alpha-methyl 2-deoxy-lyxo-pyranoside 14-alpha, and then 16 and 18 were coupled in CH2Cl2 at 23-degrees-C by using Nicolaou's NBS thioglycosidation procedure to give the alpha,alpha-disaccharide 4a with > 6:1 selectivity. Difficulties encountered in the hydrolysis or activation of the methyl glycoside function of 4a prompted the synthesis to be revised by using intermediates containing more easily deprotected anomeric silyl (TBDMS) ethers. Diol 11 was thus selectivity monosilylated to give 21, which was smoothly converted via 2-deoxy-lyxo-pyranose 23 into thioglycoside 18 and 2-deoxypyranoside 27, which possesses a TBMDS protecting group at the anomeric center. Intermediates 18 and 27 were coupled again by using the Nicolaou methodology in a CH3CN-THF cosolvent mixture at -42-degrees-C to give the AB disaccharide TBDMS acetal 4b with greater-than-or-equal-to 20:1 selectivity. Deprotection of the anomeric TBDMS acetal by using Et3NH+F- in CH3CN then completed the synthesis of the olivomycin AB disaccharide unit 4c.