Catalytic asymmetric allylation of aldehydes with allylic trialkylstannanes was achieved with BINAP•AgOTf complex as catalyst. The chiral silver(I) catalyst was readily prepared by stirring an equimolar mixture of BINAP and silver(I) triflate in THF at room temperature. The allylation of a variety of aromatic and α,β-unsaturated aldehydes resulted in high yields and remarkable enantioselectivities
Lewis Acid-Mediated Carboxylation of Aryl- and Allylsilanes with Carbon Dioxide
作者:Tetsutaro Hattori、Yutaka Suzuki、Sotaro Miyano
DOI:10.1246/cl.2003.454
日期:2003.5
Aryl- and allylsilanes are carboxylated with CO2 with the aid of aluminum-based Lewis acids, to give aromatic and β,γ-unsaturated carboxylic acids in fair to good yields, respectively. Formation of the former is rationalized by an aromatic electrophilic substitution by CO2 activated by the Lewis acid, while the latter a nucleophilic addition of in situ-generated allylaluminum species to CO2.
HIGHLY SELECTIVE INTRODUCTION OF CONJUGATED DIENES TO GOOD DIENOPHILES, α,β-UNSATURATED CARBONYL COMPOUNDS AND<i>p</i>-QUINONES, WITHOUT FORMATION OF DIELS–ALDER ADDUCT
The reaction of 2,4-pentadienyltrimethylstannane with α,β-unsaturated carbonylcompounds and p-quinones in the presence of Lewis acid affords the corresponding pentadienylated products in fair to good yield without formation of any Diels–Alder adduct.
Reactions between Pentadienyltins and 1,2-Naphthoquinones, Regiocontrolled Introduction of Pentadienyl Group
作者:Yutaka Nishigaichi、Akio Takuwa
DOI:10.1246/cl.1990.1575
日期:1990.9
efficiently pentadienylated at their 4-position with usa of pentadienyltin (PDT) reagents. Regiochemistry of the introduced pentadienyl moiety, α, γ, or e position of the PDT, was controlled by both the reaction conditions and the reactants.
Reaction of aldehydes with (E)-2,4-pentadienyltributyltin or trimethyltin in the presence of a catalytic amount of BINAP•silver(I) complex affords the corresponding γ-pentadienylated optically active alcohols with high enantioselectivities.