Enantioselective synthesis of trans-fused bicyclo[5.3.0]decane systems via a tandem [4+3] cycloaddition-Nicholás reaction
作者:Ángel M. Montaña、David Fernández
DOI:10.1016/s0040-4039(99)01336-2
日期:1999.8
0]decane systems is presented. It is a very versatile methodology based on two key reactions: [4+3] cycloaddition reaction (to generate the seven-membered ring) and the Nicholas reaction (that facilitates the insertion of the five-membered ring). This methodology allows the easy preparation of a wide range of bioactive natural products containing the trans-fused bicyclo[5.3.0]decane system. The application
New methodology for the [4+3] cycloaddition reactions: generation of oxyallyl cations from α,α′-diiodoketones under sonochemical or thermal conditions
作者:Angel M Montaña、Pedro M Grima
DOI:10.1016/s0040-4039(01)01671-9
日期:2001.10
A new methodology to perform [4+3] cycloaddition reactions of suitable dienes and 1,3-dimethyl-2-oxyallyl cations is presented. The reaction is carried out starting from commercially available dienes and easy-handling α,α′-diiodoketones, which are reduced by the Zn/Cu couple to generate the oxyallyl cation as intermediate. The reaction is carried out under mild thermal or sonochemical conditions at
Asymmetric synthesis of seven-carbon segments of the phorboxazoles and (−)-discodermolide: Complementary route from racemic trans-2,4-dimethyl-8-oxabicyclo[3.2.1]oct-6-en-3-one
作者:Andrea M Misske、H.M.R Hoffmann
DOI:10.1016/s0040-4020(99)00127-1
日期:1999.4
The C20–C26 segment of the phorboxazoles A and B and the C1–C7 segment of (−)-discodermolide were synthesized in excellent chemical and optical yield using trans-2,4-dimethyl-8-oxabicyclo[3.2.1]oct-6-en-3-one rac-1 with four stereogenic centres and three prostereogenic sp2-sites as an early racemic switch.
Generation of Oxyallyl Cations by Reduction of α,α′-Diiodoketones Under Sonochemical or Thermal Conditions: Improved Methodology for the [4C(4π;)+3C(2π;)] Cycloaddition Reactions
作者:Angel M. Montaña、Pedro M. Grima
DOI:10.1081/scc-120015712
日期:2003.3
An improved methodology to carry out [4C(4pi)+3C(2pi)] cycloaddition reactions of dienes and oxyallyl cations, is presented. The reaction starts from commercially available dienes and easy-handling alpha,alpha-diio-doketones, which are reduced by Zn (powder) or Zn/Cu couple to generate an oxyallyl cation as an intermediate. The reaction is carried out under mild thermal or sonochemical conditions at low tempera tures (from 0 to -44degreesC) and for short reaction times (< 15 min).