3113-95-9Relevant academic research and scientific papers
Method for Catalytic Enantioselective Alkylation of Aldehydes Using Grignard Reagents as Alkyl Sources
Tanaka, Kento,Tomihama, Munehisa,Yamamoto, Koji,Matsubara, Naoki,Harada, Toshiro
, p. 6127 - 6132 (2018)
Alkyltitanium reagents, generated in situ from Grignard reagents and ClTi(OiPr)3, can be employed without further manipulation in the enantioselective alkylation of aldehyde by the catalysis of a chiral titanium complex derived from DTBP-H8-BINOL. The reaction is performed with good stoichiometry [1.5 equiv each of Grignard reagents and ClTi(OiPr)3] at a low catalyst loading (2 mol %), affording a variety of chiral secondary alcohols in high enantioselectivity and yields and, hence, realizing an asymmetric version of the Grignard reaction in an indirect manner.
Room temperature and highly enantioselective additions of alkyltitanium reagents to aldehydes catalyzed by a titanium catalyst of (R)-h 8-binol
Li, Qinghan,Gau, Han-Mou
experimental part, p. 929 - 939 (2012/06/29)
Three alkyltitanium reagents of RTi(O-i-Pr)3 (R = Cy (1a), i-Bu (1b), and n-Bu (1c)) were prepared in good yields. The high-resolution mass spectroscopy showed that 1b and 1c in the gas phase are monomeric species. However, the solid state of 1a revealed a dimeric structure. Asymmetric additions of 1a-1c to aldehydes catalyzed by a titanium catalyst of (R)-H 8-BINOL were studied at room temperature. The reactions produced desired secondary alcohols in good yields with good to excellent enantioselectivities of up to 94% ee. Reactivity and enantioselectivity differences, in terms of steric bulkiness of the R nucleophiles, are herein described. The addition reactions of secondary c-hexyl to aldehydes were slower than the reactions of primary i-butyl or n-butyl nucleophiles. For the primary alkyls, lower enantioselectivities were obtained for products from addition reactions of the linear n-butyl as compared with the enantioselectivities of products from the addition reactions of the branched i-butyl group. The same stereochemistry of RTi(O-i-Pr)3 addition reactions as the addition reactions of organozinc, organoaluminum, Grignard, or organolithium reagents directly supports the argument of that titanium-catalyzed addition reactions of aldehydes involve an addition of an organotitanium nucleophile.
