An efficient and readily modifiable synthesis of GEX1A/herboxidiene/TAN-1609 (1) was developed. This modular synthesis featured a Suzuki coupling to install the conjugated diene and a Ru-catalyzed lactonization and Roush crotylation to construct the functionalized tetrahydropyran moiety. Myers' alkylation, cross-metathesis, and Keck crotylation were employed for assembly of the biologically essential side-chain domain.
An efficient and readily modifiable synthesis of GEX1A/herboxidiene/TAN-1609 (1) was developed. This modular synthesis featured a Suzuki coupling to install the conjugated diene and a Ru-catalyzed lactonization and Roush crotylation to construct the functionalized tetrahydropyran moiety. Myers' alkylation, cross-metathesis, and Keck crotylation were employed for assembly of the biologically essential side-chain domain.
Chelation controlled diastereofacial selectivity in crotyltri--butylstannane additions to α-alkoxyaldehydes
作者:Gary E. Keck、Eugene P. Boden
DOI:10.1016/s0040-4039(01)90065-6
日期:1984.1
Lewis acid mediated additions of crotyltri-n-butylstannane to chiral α-alkoxyaldehydes generally show excellent (⩾99:1) diastereofacialselectivity; proper choice of lewis acid is crucial for controlling erythro/threo selectivity in the bond formation.
Effects of Olefin Geometry on the Stereochemistry of Lewis Acid Mediated Additions of Crotylstannanes to Aldehydes
作者:Gary E. Keck、Kenneth A. Savin、Erik N. K. Cressman、Duane E. Abbott
DOI:10.1021/jo00104a054
日期:1994.12
The role of the double bond geometry (E/Z stereochemistry) in reactions of crotylstannanes with aldehydes has been examined for representative ''simple'', alpha-alkoxy, and beta-alkoxy aldehydes. For the reaction of crotylstannane with simple achiral aliphatic, aromatic, or alpha,beta unsaturated aldehydes mediated by BF3.Et(2)O, use of the E crotylstannane gives much enhanced syn selectivity over that obtained with Z (e.g., 43:1 vs 4:1 with benzaldehyde). A synclinal transition state in which the CH(2)SnBu(3) group is gauche to oxygen is proposed to explain these results. For alpha-alkoxy aldehydes, use of the E stannane with MgBr2 gives the highest syn selectivity, while the Z stannane gives slightly better stereoselectivity with beta-alkoxy substrates. In contrast, the use of TiCl4 gives anti products preferentially from the E stannane and either alpha or beta-alkoxy substrates.
Total Synthesis of GEX1A
作者:Timothy J. Murray、Craig J. Forsyth
DOI:10.1021/ol800902g
日期:2008.8.21
An efficient and readily modifiable synthesis of GEX1A/herboxidiene/TAN-1609 (1) was developed. This modular synthesis featured a Suzuki coupling to install the conjugated diene and a Ru-catalyzed lactonization and Roush crotylation to construct the functionalized tetrahydropyran moiety. Myers' alkylation, cross-metathesis, and Keck crotylation were employed for assembly of the biologically essential side-chain domain.