Asymmetric Synthesis of Synargentolide A and Its 3-Epimer Using the RAMP-Hydrazone Methodology
摘要:
Synargentolide A was synthesized in 11 steps starting from the commercially available 2,2-dimethyl-1,3-dioxan-5-one, employing the SAMP/RAMP-methodology via an alpha,alpha'-bis-alkylation to generate the first two stereogenic centers with virtually complete asymmetric induction (de, ee > 99%). After the asymmetric synthesis of the triol fragment of the molecule, the delta-lactone moiety was constructed using an asymmetric allylation, esterification, and ring-closing metathesis sequence.
Indium-mediated allylation of aldehydes: A convenient route to 2-deoxy and 2,6-dideoxy carbohydrates
摘要:
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.
Stereochemistry of the reactions of substituted allylboronates with chiral aldehydes. Factors influencing aldehyde diastereofacial selectivity
作者:William R. Roush、Michael A. Adam、Alan E. Walts、David J. Harris
DOI:10.1021/ja00272a043
日期:1986.6
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.
Asymmetric Synthesis of Synargentolide A and Its 3-Epimer Using the RAMP-Hydrazone Methodology
作者:Dieter Enders、Linus Reichenbach
DOI:10.1055/s-0032-1316865
日期:——
Synargentolide A was synthesized in 11 steps starting from the commercially available 2,2-dimethyl-1,3-dioxan-5-one, employing the SAMP/RAMP-methodology via an alpha,alpha'-bis-alkylation to generate the first two stereogenic centers with virtually complete asymmetric induction (de, ee > 99%). After the asymmetric synthesis of the triol fragment of the molecule, the delta-lactone moiety was constructed using an asymmetric allylation, esterification, and ring-closing metathesis sequence.