Catalytic Allylation of Aldehydes Using Unactivated Alkenes
作者:Shun Tanabe、Harunobu Mitsunuma、Motomu Kanai
DOI:10.1021/jacs.0c04735
日期:2020.7.15
and a chromium complex catalyst, enabling catalytic allylation of aldehydes with simplealkenes, including feedstock lower alkenes. The reaction proceeded under visible-light irradiation at room temperature and with high functional group tolerance. The reaction was extended to an asymmetric variant by employing a chiral chromium complex catalyst.
α,α-Diisopropylhomoallylic alcohols react with tin(II) chloride and NCS in CH2Cl2 at -40 °C to -60 °C to produce allylic tins and diisopropyl ketone, and the allylic tins in situ cause nucleophilic addition to aldehydes to afford α-substituted homoallylic alcohols.
diastereoselective. The allylation of benzaldehyde by 1-chlorobut-2-ene in 1,3-dimethylimidazolidin-2-one (DMI) does not occur with tin(II) chloride or bromide but does proceed with tin(II) iodide and exhibits gamma-syn selectivity which is unusual for a Barbier-type carbonylallylation. In the carbonylallylation by 1-chlorobut-2-ene with any tin(II) halide, the addition of tetrabutylammoniumiodide (TBAI) accelerates
nBu4NBr/PbI2 acts as an effective catalyst for the allylation of aldehydes 2 with the allylic tin reagents 1 in water. A high syn-selectivity of 3 was achieved in water without any aprotic solvents in the reaction of the aromatic aldehydes 2 with the crotyltri-n-butyltin reagents 1b, 1c irrespective of their E/Z geometry.