Studies on the Synthesis of Bafilomycin A<sub>1</sub>: Stereochemical Aspects of the Fragment Assembly Aldol Reaction for Construction of the C(13)−C(25) Segment
作者:William R. Roush、Thomas D. Bannister、Michael D. Wendt、Jill A. Jablonowski、Karl A. Scheidt
DOI:10.1021/jo016413f
日期:2002.6.1
lithium enolate aldolreaction. In contrast, the aldolreaction of 6a and the chlorotitanium enolates of 7a,c were much less sensitive to the nature of the C(15)-hydroxyl protectinggroup. Studies of the reactions of chiral aldehydes with Takai's (gamma-methoxyallyl)chromium reagent 40 are also described. The stereoselectivity of these reactions is also highly dependent on the protectinggroups and stereochemistry
Total synthesis of the ionophore antibiotic CP-61,405 (routiennocin)
作者:David Díez-Martin、Nikesh R. Kotecha、Steven V. Ley、Sergio Mantegani、J.Carlos Menéndez、Helen M. Organ、Andrew D. White、Bernard J. Banks
DOI:10.1016/s0040-4020(01)80467-1
日期:1992.1
The totalsynthesis of the spiroketal ionophore antibiotic routiennocin 1 (CP-61,405) employing π-allyltricarbonyl iron lactone complexes is described. These complexes were used as precursors for the preparation of substituted 2-phenylsulphonyl pyrans which, in turn, were coupled with iodoacetonides to afford spiroketals. Elaboration of the spiroketals by tetra-n-propylammonium perruthenate (TPAP)
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.
Crotylzirconium derivatives as a new reagent for the threo selective synthesis of β-methylhomoallyl alcohols
作者:Yoshinori Yamamoto、Kazuhiro Maruyama
DOI:10.1016/s0040-4039(01)81780-9
日期:1981.1
Stereoselective synthesis of the C(13)–C(25) segment of bafilomycin A1
作者:William R. Roush、Thomas D. Bannister
DOI:10.1016/s0040-4039(00)92509-7
日期:1992.6
The aldol reaction of 2 and the lithium enolate of 3 provides the bafilomycin C(13)-C(25) fragment 1 with 8 : 1 stereoselectivity.