4974-92-9Relevant academic research and scientific papers
Investigating the π-facial discrimination phenomenon in the conjugate addition of amines to chiral crotonates: A convenient basis for the rational design of chiral auxiliaries
Dumas, Francoise,Mezrhab, Brahim,D'Angelo, Jean,Riche, Claude,Chiaroni, Angele
, p. 2293 - 2304 (2007/10/03)
This paper is concerned with the nature of the chiral inducer in the high pressure-induced conjugate addition of amines to auxiliary-tethered crotonates. Almost complete stereocontrol was obtained in the addition of diphenylmethanamine to crotonates derived from the "arylmenthol" auxiliaries 18a, 18c, and 4 bearing an o-methoxyphenyl, p-phenoxyphenyl, or β-naphthyl substituent, respectively. This high efficiency has been attributed to the predominance of stacked conformations in such crotonates, a hypothesis supported by the 1H NMR spectra, calculated energy of conformational optima of the corresponding crotonates, and X-ray crystal structure of 5a. The arene and enoate appendages are roughly coplanar, separated by 3.4-4 A. In contrast, only moderate selectivities could be achieved using various trans-2-arylcyclohexanols (27, 28, 2c, 29) as auxiliaries. In these cases the efficiency appears to be seriously compromised by the "widening V" arrangement exhibited by the two π-systems, as shown in the X-ray crystal structures of crotonates 5h and 5k. The sense of stereochemical induction of this conjugate addition has been determined by condensing diphenylmethanamine with enantiopure crotonate (+)-5a. The adduct 9a was converted to amino alcohol (S)-11, of known configuration. This correlation is consistent with the preferential attack of the amine to the less sterically hindered enoate π-face of (+)-5a, in its s-trans conformation. Finally, the stereochemistry of the proton transfer was determined by adding N,N-dideuteriodiphenylmethanamine to crotonate (±)-5a. The stereochemical outcome of this addition is consistent with the anti-addition of the incoming nitrogen nucleophile and the deuterium atom.
SYNTHESIS AND REACTIVITY OF ARYLOXYCUMENYL CHLORIDES
Litvinenko, L. M.,Benndorf, V.,Popova, R. S.,Popov, A. F.,Tormosin, I. I.
, p. 680 - 683 (2007/10/02)
A series of derivatives of aryloxycumenyl chlorides containing substituents (methyl, methoxy, fluorine, and chlorine) at positions 3 and 4 of the aryl ring were synthesized.From the results from their solvolysis in 90 vol. percent aqueous acetone it was concluded that there is strong transfer of the electronic effects through the diphenyl ether system comparable with that in biphenyl.
