33967-19-0Relevant articles and documents
FLP-Catalyzed Transfer Hydrogenation of Silyl Enol Ethers
Khan, Imtiaz,Reed-Berendt, Benjamin G.,Melen, Rebecca L.,Morrill, Louis C.
, p. 12356 - 12359 (2018/09/18)
Herein we report the first catalytic transfer hydrogenation of silyl enol ethers. This metal free approach employs tris(pentafluorophenyl)borane and 2,2,6,6-tetramethylpiperidine (TMP) as a commercially available FLP catalyst system and naturally occurring γ-terpinene as a dihydrogen surrogate. A variety of silyl enol ethers undergo efficient hydrogenation, with the reduced products isolated in excellent yields (29 examples, 82 % average yield).
Dynamic path bifurcation in the Beckmann reaction: Support from kinetic analyses
Yamamoto, Yutaro,Hasegawa, Hiroto,Yamataka, Hiroshi
, p. 4652 - 4660 (2011/07/29)
The reactions of oximes to amides, known as the Beckmann rearrangement, may undergo fragmentation to form carbocations + nitriles when the migrating groups have reasonable stability as cations. The reactions of oxime sulfonates of 1-substituted-phenyl-2-propanone derivatives (7-X) and related substrates (8-X, 9a-X) in aqueous CH3CN gave both rearrangement products (amides) and fragmentation products (alcohols), the ratio of which depends on the system; the reactions of 7-X gave amides predominantly, whereas 9a-X yielded alcohols as the major product. The logk-logk plots between the systems gave excellent linear correlations with slopes of near unity. The results support the occurrence of path bifurcation after the rate-determining TS of the Beckmann rearrangement/fragmentation reaction, which has previously been proposed on the basis of molecular dynamics simulations. It was concluded that path-bifurcation phenomenon could be more common than thought and that a reactivity-selectivity argument based on the traditional TS theory may not always be applicable even to a well-known textbook organic reaction.
Preparation of chiral 1-phenylethanols and bromides
Stein, Allan R.,Dawe, Robert D.,Sweet, James R.
, p. 3442 - 3448 (2007/10/02)
A fast, convenient procedure for preparing and resolving moderate to large quantities of chiral secondary alcohols is described.The general procedure involves a one-pot conversion of the ketone (various acetophenones) to the half-ester of a diacid (succinic, phthalic...) and resolution with (+)- and (-)-1-phenylethylamines.Overall yields of the enantiomeric alcohols, the variously substituted 1-phenylethanols, are generally 65-85percent with optical purities of approximately 90percent.Properties and optical rotations of a number of chiral 1-phenylethanols and of the bromides made from them are tabulated.A discussion of optical purity determinations using nmr methods is included and absolute configurations are reported.