1,720,977 research outputs found
A novel chiral synthetic equivalent of glyoxal and its application to the asymmetric synthesis of O-protected a-hydroxy aldehydes
No full textNovel stereoselective syntheses of (2E,4E)-4-(4,4-dimethylpent-2-ynylidene)-N1,N5-dimethyl-N1,N5-bis(naphthalen-1-ylmethyl)pent-2-ene-1,5-diamine
No full textWe report two different synthetic approaches for the stereoselective synthesis of (2E,4E)-4-(4,4-dimethylpent-
2-ynylidene)-N1,N5-dimethyl-N1,N5-bis(naphthalen-1-ylmethyl)pent-2-ene-1,5-diamine 1, an
important impurity-reference standard for the chemical characterization of terbinafine. The diamine 1
was obtained in only six steps with a good overall yield starting from commercially available glutaconic
acid
New fast and practical method for the enantioselective synthesis of α-vinyl, α-alkyl quaternary α-amino acids
No full textWe describe a fast and practical enantioselective synthesis of (S)-N-Cbz-a-vinyl, phenylalanine, suitable for the preparation of
different N-Cbz-a-vinyl aminoacids of both configurations. The new protocol exploits a Wittig reaction on highly enantiomeric enriched
N-Cbz-a-formyl-a-alkyl amino esters, readily accessible from (L)-serine through a stereoselective alkylation of Seebach’s oxazolidine,
carried out with a significant improvement of the previously reported method. The synthetic scheme is suitable for gram scale preparation
of the desired product with a 94% e
Synthesis of bicyclolactam (Phe-Pro)-mimetic scaffold using an intramolecular Hosomi-Sakurai reaction
No full textStereoselective Pd-catalyzed synthesis of quaternary a-C-D-mannosyl-(S)-amino acids
No full textIn this paper, we report the stereoselective synthesis of α-d-C-mannosyl-(S)-amino acids exploiting, as a key step, an allylic alkylation of glycal-derived π-allyl Pd(II) intermediates, prepared by oxidative addition of Pd(0) species to 2,3-unsaturated pyranosides (pseudoglycals). The reaction of 4,6-di-O-acetyl α-pseudoglucal carbonate 10a with racemic alanine-, valine-, and phenylalanine-derived azlactones gave the corresponding (4S)-4-α-d-C-mannosyl-2-phenyloxazol-5(4H)-ones as the major diastereoisomers in high yields. The final α-d-C-mannosyl-(S)-amino acids were obtained in a few steps comprising highly diastereoselective dihydroxylation of the glucal derivative double bond followed by the one-pot hydrolysis of the benzamido and acetate protecting groups. Main features of this method are the conciseness of the synthetic sequence, the high diastereoselection of the allylic alkylation step, the use of racemic α-amino acids as starting material, and the good overall yields
Conformationally constrained dipeptides:synthesis of bicyclic lactams by stereoselective radical cyclizations
No full textSynthesis of a preclavulones analogous:(±)- 8,12-trans-(5Z,14Z)-9-oxo-prosta-5,10,14-trienoic acid methyl ester via its 10-11 dihydroprecursor from allyl 2-oxo-cyclopentanecarboxylate
No full textSimple (R) chirally induced syntheses of (+)-(2E,4E,8Z)-ethyl 6-tetrahydropyranyloxytetradeca-2,4,8-trienoate, a versatile prosynthon C-14 for LTB4
No full textWe report the asymmetric synthesis of title compound, a prosynthon at C14 for LTB4, obtained using two different chiralizing agent
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