88762-93-0Relevant articles and documents
A dimethylzinc/diphenylphosphinoylimine approach to the asymmetric synthesis of the calcimimetic agent NPS R-568
Banerjee, Sucharita,Smith, Brad,Hitchcock, Shawn R.
experimental part, p. 105 - 109 (2012/06/18)
An asymmetric synthesis of the calcimimetic agent NPS R-568 using a (1R,2S)-N-benzylephedrine-promoted addition of dimethylzinc to a diphenylphosphinoylimine derived from 3-methoxybenzaldehyde is described. The enantiomeric ratio of the key amine fragment was determined to be 93:7 (86% ee), favoring the (R)-enantiomer by derivatization and chiral stationary phase HPLC analysis.
Enantiospecific Stereodivergent Synthesis of trans- and cis-N(2), 3-Dimethyl- 4-phenyl-1, 2, 3, 4-tetrahydroisoquinolines
Coote, Steven J.,Davies, Stephen G.,Fletcher, Ai M.,Roberts, Paul M.,Thomson, James E.
experimental part, p. 589 - 604 (2010/08/07)
The acid-promoted cyclizations of a range of N-benzylethanolamines (derived from pseudoephedrine or ephedrine) give the corresponding trans-N(2), 3-dimethyl-4-phenyl-1, 2, 3, 4- tetrahydroisoquinolines with high levels of diastereoselectivity and in good yields of isolated product. The cyclizations of the corresponding chromium tricarbonyl complexes are rendered completely stereoselective. Acidpromoted cyclization of N-(3′, 4′- dimethoxybenzyl) ephedrine and its chromium tricarbonyl complex occur with complementary diastereoselectivities to give trans- and cis-N(2), 3-dimethyl-4- phenyl-6, 7-dimethoxy-1, 2, 3, 4-tetrahydro- isoquinoline, respectively, in >99:1 d.r. The latter is consistent with a "double inversion" mechanism, which involves neighboring group participation by the chromium tricarbonyl moiety followed by rearomatization to give the corresponding cis-tetrahydroisoquinoline with overall retention of configuration.
Enantioselective diethylzinc addition to the exocyclic C{double bond, long}N double bond of some 4-arylideneamino-3-mercapto-6-methyl-4H-1,2,4-triazin-5-one derivatives
El-Shehawy, Ashraf A.
, p. 2617 - 2624 (2007/10/03)
4-Arylideneamino-3-mercapto-6-methyl-4H-1,2,4-triazin-5-ones 2a-f have been evaluated as substrates in the enantioselective diethylzinc addition reaction in the presence of (1S,2R)-N-alkyl-N-benzylnorephedrines 3a-d as chiral ligands. The utility of using a dual catalytic system (amino alcohol/halosilane) for the diethylzinc addition reaction has been also examined. The addition products 4-(1-arylpropyl)amino-3-mercapto-6-methyl-4H-1,2,4-triazin-5-ones 4a-f were obtained in high yields and with enantiomeric excesses of up to 92%. The treatment of arylimines 2a-f with a diethylzinc reagent did not affect the hetero-ring opening although the C{double bond, long}N double bond of the lateral chain did undergo an addition reaction to yield the C-ethylated products 4a-f. The reductive cleavage of the 1,2,4-triazinyl heterocyclic ring from addition products 4a-f led smoothly to the corresponding free primary amines 5a-f without a significant loss of enantiomeric purity.
