124389-41-9Relevant academic research and scientific papers
Mesoporous aluminosilicate-catalyzed allylation of carbonyl compounds and acetals
Ito, Suguru,Hayashi, Akira,Komai, Hirotomo,Yamaguchi, Hitoshi,Kubota, Yoshihiro,Asami, Masatoshi
, p. 2081 - 2089 (2011/04/19)
A mesoporous aluminosilicate (Al-MCM-41) was found to be an effective heterogeneous catalyst for the reaction of both carbonyl compounds and acetals with allylsilanes to afford the corresponding homoallyl silyl ethers and homoallyl alkyl ethers, respectively. Both the mesoporous structure and the presence of aluminum moiety were indispensable for the high catalytic activity of Al-MCM-41. Moreover, Al-MCM-41 could catalyze the reaction of acetals chemoselectively in the presence of the corresponding carbonyl compounds. The solid acid catalyst Al-MCM-41 could be recovered easily by filtration and could be reused three times without a significant loss of catalytic activity.
Facile preparation of allylzinc species from allyl bromides and unactivated zinc induced by a catalytic amount of aluminum chloride and their reactions with carbonyl compounds and acetals
Maeda,Shono,Ohmori
, p. 1808 - 1812 (2007/10/02)
The effects of Lewis acids (ZnCl2, AlCl3, BF3, and TiCl4) on the generation of allylzinc species from allyl bromide and unactivated zinc powder in dry tetrahydrofuran (THF) were examined by trapping the organozinc compound with benzaldehyde, that is, Grignard-type allylation of the aldehyde. Among the Lewis acids employed, AlCl3 was found to be the promoter of choice. The allylzinc species preformed in the presence of a catalytic amount of AlCl3 effectively allylated carbonyl compounds. Various aromatic and aliphatic aldehydes as well as ketones were converted into homoallylic alcohols in good to excellent yields. Under the reaction conditions employed, ester, hydroxy, acetal, and aromatic nitro and halide groups were tolerated. In the case of α,β-unsaturated carbonyl compounds, selective 1,2-addition was observed. Substituted allyl bromides such as prenyl, crotyl, cinnamyl, and 2-cyclohexenyl bromides were smoothly converted to the corresponding allylzinc compounds, which reacted with carbonyl compounds to give substituted homoallylic alcohols in excellent yields. The diastereoselectivity in crotylation, cinnamylation, and 2-cyclohexenylation depended upon the structures of both the organic metals and the electrophiles. The origin of the observed selectivity is discussed. The allylation of dimethyl and cyclic acetals accompanied with carbon-oxygen bond cleavage also proceeded in excellent yields provided that two equivalents of AlCl3 was present.
Allylation Using Allylborates
Hunter, Roger,Michael, Joseph P.,Tomlinson, Geoffrey D.
, p. 871 - 888 (2007/10/02)
A study has been carried out on the scope of allylation of a range of acetals activated by trimethylsilyl trifluoromethanesulfonate (TMSOTf) using a number of organoborates.Intermolecular allylation of acyclic acetals proceeds smoothly and in high yield using lithium n-butyltriallylborate or lithium methyltriallylborate in THF at -78 deg C while 1,3-dioxanes and dioxolanes give rise to some reduction products.Intramolecular allylation may be carried out via anchoring the triallylborane using an alkoxide anion.Mechanistic studies indicate that allyl transfer is from boron and not silicon, while stereoselectivity studies on the crotylation of acyclic acetals as well as the allylation of chiral acetals derived from (2R,4R)-pentanediol indicate moderate levels of diastereoselection.
ALLYLATION USING ORGANOBORATES AND ACTIVATED ACETALS
Hunter, Roger,Tomlinson, Geoffrey D.
, p. 2013 - 2016 (2007/10/02)
Lithium n-butyltriallylborate intermolecularly allylates a range of acetals activated by TMSOTF.The reaction may also be accomplished intramolecularly.
