Synthesis of Termini-Differentiated 6-Carbon Stereotetrads: An Alkylative Oxidation Strategy for Preparation of the C21−C26 Segment of Apoptolidin<sup>1</sup>
作者:Yuzhong Chen、Jerry B. Evarts、Eduardo Torres、Philip L. Fuchs
DOI:10.1021/ol026377m
日期:2002.10.1
an enantiospecific catalytic Jacobsen epoxidation of 1a and is five operations shorter. The second sequence features an oxygen-directed alkylativeoxidation reaction that re-establishes the dienyl sulfonefunctionality with concomitant 1,3-transposition of the sulfone moiety.
Conjugate addition reactions of a (diethoxyphosphinoyl)difluoromethyl anion equivalent to acyclic and cyclic vinyl sulfones
作者:K. Blades、D. Lapôtre、J.M. Percy
DOI:10.1016/s0040-4039(97)01313-0
日期:1997.8
Cerium-mediated conjugateadditions of (diethoxyphosphinoyl)difluoromethyllithium to cyclic vinylsulfones proceeded smoothly; reduction afforded the products of formal alkylation, attaching the difluoromethylene phosphonate group to a secondary carbon atom. With acyclic vinylsulfones, the addition was considerably less efficient and deprotonation competed with addition. Addition failed completely
A general approach to the synthesis of enantiopure 19-nor-Vitamin D3 and its C-2 phosphate analogs prepared from cyclohexadienyl sulfone
作者:Vikas Sikervar、James C. Fleet、Philip L. Fuchs
DOI:10.1039/c2cc33054g
日期:——
A synthesis of enantiopure 19-nor-Vitamin D(3) and its C-2 substituted cyclic phosphateanalogs is achieved via in situ trapping of an alpha-sulfonyl anion with a CD-ring allyl chloride and 1,2-eliminative desulfonylation exploiting the basic properties of TBAF. The A-ring is prepared via anti-selective dithiane addition to vinyl sulfone and LiBH(4) mediated sequential bis reduction of an epoxy vinyl
[GRAPHICS]Enantiopure epoxy vinyl sulfones serve as highly effective substrates for a variety of stereo- and regiospecific oxidation and nucleophilic functionalization reactions. These materials can be easily transformed to cyclic and acyclic six carbon segments. Nucleophilic epoxidation of 3a,b followed by palladium[0] catalysis enables access to differentially protected arene diols 21 and 22.
Jacobsen Protocols for Large-Scale Epoxidation of Cyclic Dienyl Sulfones: Application to the (+)-Pretazettine Core
作者:G. Reza Ebrahimian、Xavier Mollat du Jourdin、Philip L. Fuchs
DOI:10.1021/ol300996m
日期:2012.5.18
A Jacobsen epoxidation protocol using H2O2 as oxidant was designed for the large-scale preparation of various epoxy vinyl sulfones. A number of cocatalysts were screened, and pH control led to increased reaction rate, higher turnover number, and improved reliability.
设计了一种以H 2 O 2为氧化剂的Jacobsen环氧化方案,用于大规模制备各种环氧乙烯基砜。筛选了许多助催化剂,控制pH值可提高反应速率,提高周转次数并提高可靠性。