The synthesis of 1-aminobenzylphosphonic acids from benzylidenediphenylmethylamines, for use as structural units in antithrombotic tripeptides
摘要:
Acid hydrolyses of 0,0-dimethyl or 0,0-diethyl 1-(diphenylmethylamino) benzylphosphonate intermediates 2, formed from the addition at elevated temperature of dimethyl or diethyl phosphite to benzylidenediphenylmethylamines 1, generates 1-aminobenzylphosphonic acids 3 in good yield.
A catalyticenantioselectiveStreckerreaction catalyzed by novel chiral lanthanum(III)−binaphthyl disulfonate complexes was developed. The key to promoting the reactions was a semistoichiometric amount of AcOH or i-PrCO2H, which takes advantage of HCN generation in situ. The corresponding cyanation products were obtained in high yields and with high enantioselectivities.
Catalytic asymmetric Strecker hydrocyanation of imines using Yb(OTf)3–pybox catalysts
作者:Babak Karimi、Aziz Maleki
DOI:10.1039/b908854g
日期:——
We have explored the highly enantioselective Strecker hydrocyanation of a wide range of aromatic, α,β-unsaturated, heterocyclic, and aliphatic aldimines with good to excellent conversions and ees up to 98% in the presence of catalytic amounts of Yb(OTf)3âpybox complexes.
Described herein are compounds of formula (I), related compositions, and their use, for example in the formation of α-amino acids or a precursor thereof such as an α-aminonitrile.
A practical procedure for catalytic asymmetric synthesis of opticallyactive arylglycine derivatives viaopticallyactive α-aminonitriles has been developed. The N-benzhydryl α-arylaminonitrile intermediates were prepared in excellent yield (89–99%) and enantiomeric purity (96 to >98% ee) by enantioselective cyanation of aldimines with TMSCN/iPrOH in the presence of 2.5 mol % of an easily prepared
Nucleophilic Trifluoromethylation of Imines under Acidic Conditions
作者:Vitalij V. Levin、Alexander D. Dilman、Pavel A. Belyakov、Marina I. Struchkova、Vladimir A. Tartakovsky
DOI:10.1002/ejoc.200800820
日期:2008.11
A general method for the trifluoromethylation of imines by using Me3SiCF3 under acidic conditions is described. The reaction is promoted by hydrofluoric acid generated in situ from KHF2 and either TFA or TfOH. A new chemoselectivity pattern was achieved, as the C=N bond was found to be more reactivate than the carbonyl group. The trifluoromethylation reaction is believed to proceed by concerted transfer