38281-40-2Relevant academic research and scientific papers
Bis(μ-oxo)-Dititanium(IV)-Chiral Binaphthyldisulfonate Complexes for Highly Enantioselective Intramolecular Hydroalkoxylation of Nonactivated Alkenes
Xie, Wen-Bin,Li, Zhi
, p. 6270 - 6275 (2021)
A series of chiral 1,1′-binaphthyl-2,2′-disulfonic acids was designed, synthesized, and applied in a highly enantioselective Ti-catalyzed intramolecular hydroalkoxylation of nonactivated alkenes. The catalyst is probably a complex between two chiral binaphthyldisulfonate ligands and a bis(μ-oxo)-dititanium(IV) core structure. The sulfonamide groups of the ligands and water are necessary for the catalysis, as they may stabilize the catalytically active complex through hydrogen bonding. Various 2-methylcoumarans were obtained in up to greater than 99% yields and up to 97% enantiomeric excess under mild conditions.
Generation and Reactions of 2-Alkoxydiphenylcarbenes in Fluid Solution and Rigid Matrices
Tomioka, Hideo,Nakanishi, Keisaku,Izawa, Yasuji
, p. 465 - 470 (2007/10/02)
Irradiation of 2-alkoxydiphenyldiazomethanes 1 in cyclohexane at room temperature produced 3-phenyldihydrobenzofurans 3 presumably as a result of intramolecular C-H insertion of 2-alkoxydiphenylcarbenes 2.Irradiation of compounds 1 in cyclohexane matrix at -196 deg C gave intermolecular C-H insertion products 4 at the expense of benzofurans 3.The formation of products 4 is explicable in terms of H-atom tunnelling to the triplet state of carbenes 2, followed by coupling of the resulting radical pairs.Product ratios 3:4 were somewhat sensitive to the bulk of the alkoxy group at the 2-position.This can be explained in terms of the matrix effect on the relative population of the rotational isomers of the carbene 2.Irradiation of compounds 1 in methanol at room temperature afforded O-H insertion products 5 almost exclusively, whereas irradiation in methanol matrix at -196 deg C gave C-H insertion products 6 along with other products 3 and 5.
