cas 4629-80-5, 1,3-Dimethylpiperidin-4-one

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Selective α-Methylation of Ketones
The convenient and scalable preparative approach for the two-step α-methylation of ketones is described. The optimized protocols for regioselective preparation of enaminones with further diastereoselective and functional groups tolerant hydrogenation to α-methylketones are developed. The scope and limitations of the proposed methodology are discussed. The advantages compared to known procedures are demonstrated. The unexpected role of acetone in the hydrogenation is suggested. The evaluation of the method for both early building block synthesis and late-stage CH-functionalization is shown. The elaborate procedures' preparability and scalability are demonstrated by the synthesis of several α-methyl ketones up to 100 g amount.
Frolov, Andriy I.,Ostapchuk, Eugeniy N.,Pashenko, Alexander E.,Chuchvera, Yaroslav O.,Rusanov, Eduard B.,Volochnyuk, Dmitriy M.,Ryabukhin, Sergey V.
p. 7333 - 7346
(2021/06/28)

Functionalized chloroenamines in aminocyclopropane synthesis - X. Amino-azabicyclo[3.1.0]hexane diastereomers from chloroenamines and organometallic compounds
Morpholino-chlorotetrahydro-N-methyl-pyridine 4 reacted with Grignard reagents 5 or diorganyl-magnesium compounds 6 to give a mixture of azabicyclo[3.1.0]hexane diastereomers 10 and 11 besides the monocyclic ketones 12. The latter were obtained as the sole products from chloroenamine 4 and dimethylzinc 7a or lithium dimethylcopper 8a. Organolithium compounds 9a,c or Grignard reagents 5a-c in the presence of TMEDA transferred 4 exclusively to endo-morpholino isomers 10. exo-Amines 11 coulb be obtained with high stereoselectivity from 4 via the N,O-acetal 13 and by the substitution of the methoxy moiety by a Grignard reagent. 5. The stereochemical result of this substitution reaction can be explained by an intermediate complexation of the pyrrolidine N-atom in 13 by the Grignard reagent 5. An N-benzyl chloroenamine 14 instead of the N-methyl compound 4 showed a different reaction behavior with methylmagnesium bromide 5a leading only to endo-amine 15 which could be used as a precursor of the parent bicyclic system 16. The configurations of the bicyclic diamines 10, 11 and 15 were determined via 1H NMR data.
Butz,Vilsmaier
p. 6031 - 6044
(2007/10/02)

DETERMINATION OF THE CONFIGURATIONS OF ALCOHOLS AND ISOCYANATES BY KINETIC RESOLUTION
The kinetic resolution of α-phenylethyl isocyanate was achieved by means of R-α-phenylethylamine, and S-α-benzylethylamine, S-salsolidine.The absolute configuration of α-phenylisobutyl isocyanate was determined on the basis of the relationship discoverd during the kinetic resolution of the isocyanate with these amines.The configurations of the carbon atom carrying the hydroxyl group in the cis and trans isomer of 1,3-dimethyl-4-piperidol were determined as a result of investigation of the stereochemical relationships in the reaction of α-phenyl-ethyl isocyanatewith alicyclic alcohols.A new asymmetric catalyst (S-N-methyl-salsolidine) is proposed for the kinetic resolution of alkylphenylcarbinols with α-phenylethyl isocyanate.
Potapov, V. M.,Gracheva, R. A.,Okulova, V. F.
p. 311 - 316
(2007/10/02)