tested as chiral auxiliaries in the stereoselectivesynthesis of β-lactams by condensation of the titanium enolates of 2-pyridyl thioesters with chiral imines. The amines were selected among the following classes of compounds: benzylic amines, β-aminoalcohols, β-heterosubstituted α-aminoesters. Inexpensive and available in both enantiomeric forms α-methylbenzylamine was identified as the chiral auxiliary
Facile Synthesis of Highly Functionalized <i>N-</i>Methyl Amino Acid Esters without Side-Chain Protection
作者:Kimberly N. White、Joseph P. Konopelski
DOI:10.1021/ol051441w
日期:2005.9.1
[reaction: see text] The facile, two-pot synthesis of N-methyl aminoacid esters by way of reductiveamination is presented. Side chain protection schemes are not required, the starting materials are all commercially available, and the synthetic method is straightforward and affords desired product in very high yield.
Stereoselective Addition of Dimethyl Thiophosphite to Imines
作者:Pakamas Tongcharoensirikul、Alirica I. Suarez、Troy Voelker、Charles M. Thompson
DOI:10.1021/jo035707t
日期:2004.4.1
benzaldimine derived from threonine methyl ester and alanine methyl ester were far less diastereoselective, affording 38:62 and 61:39 ratios, respectively. Addition of DMTP to the benzaldimine derived from (R)-α-methylbenzylamine (78:22) and (S)-serine methyl ester (73:27) were intermediate in selectivity. DMTP addition to the imines formed between serine methyl ester and acetaldehyde and isobutyraldehyde
N-methyl threonine analogues of deglycobleomycin A2: Synthesis and evaluation
作者:Dale L. Boger、Shuji Teramoto、Hui Cai
DOI:10.1016/s0968-0896(97)00107-7
日期:1997.8
The synthesis of 5 and its D-allo-threonine epimer 6 and the comparison of their DNA cleavage efficiency and selectivity with that of deglycobleomycin A(2) (3) are detailed. The studies illustrate that N-methylation of the L-threonine subunit within deglycobleomycin A(2) dramatically reduces the DNA cleavage efficiency (10-15-fold), weakens and nearly abolishes the inherent DNA cleavage selectivity, but has little effect on the inherent oxidation capabilities of the activated Fe(III) complexes. The results are consistent with a previously unrecognized prominent role for the threonine NH and the potential importance of a hydrogen bond to the Fe(III) hydroperoxide complex of bleomycin or a subsequent activated complex implicated in recent structural models. (C) 1997 Elsevier Science Ltd.