Intermolecular one-pot cyclization of formyl-pyrroles of amino acid esters with norephedrine: stereoselective routes to new tricyclic pyrrole-pyrazine-oxazole fused structures

Demir, Ayhan Sıtkı
Subasi, N. Tuna
Sahin, Ertan
The treatment of esters of amino acids with dimethoxytetrahydrofuran furnished pyrrole derivatives of amino acid esters. The Wilsmeier-Haack formylation followed by the reaction of the formylated pyrroles with norephedrine afforded a selective formation of the tricyclic pyrrole-pyrazine-oxazole fused structures in one step via the formation of an oxazoline structure and intramolecular lactam formation. Pyrrole-pyrazine-oxazole fused structures were achieved in good yields. The cyclization reaction for the formation of an oxazole ring worked selectively to form only one stereoisomer. The configuration of the newly generated stereogenic center in the oxazole ring is dependent on the stereogenic centers of norephedrine.


Amination/annulation of chlorobutenones with chiral amine compounds: synthesis of 1,2,4-trisubstituted pyrroles
Demir, Ayhan Sıtkı; Igdir, AC; Gunay, NB (Elsevier BV, 2005-10-03)
A series of 1,2,4-trisubstituted pyrroles have been synthesized in 83-96% yields on treatment of chiral primary amines, amino alcohols and esters of alpha-amino acids with different chlorobutenones in benzene-triethylamine. The conversions proceed without racemization.
Novel enantioselective synthesis of both enantiomers of furan-2-yl Amines and amino acids
Demir, Ayhan Sıtkı; Sesemoglu, O; Ulku, D; Arici, C (Wiley, 2003-01-01)
A new enantioselective synthesis of furan-2-yl amines and amino acids is described, in which the key step is the oxazaborolidine-catalyzed enantioselective reduction of O-benzyl (E)- and (Z)-furan-2-yl ketone oximes to the corresponding chiral amines. The chirality of the furan-2-yl amines is fully controlled by the appropriate choice of the geometrical isomer of the O-benzyl oxime. Oxidation of the furan ring furnished amino acids in high yields.
A bis-Lewis basic 2-aminoDMAP/prolinamide organocatalyst for application to the enantioselective synthesis of Warfarin and derivatives
IŞIK, Murat; Akkoca, H. Ufuk; Akhmedov, I. Mecidoglu; Tanyeli, Cihangir (Elsevier BV, 2016-06-01)
A new chiral sec-amine/amidine-base hybrid catalyst, 2-aminoDMAP/prolinamide, is reported, which is able to catalyze conjugate addition of 4-hydroxycoumarin and various benzylideneacetones, a reaction that directly gives anticoagulant Warfarin and its analogues, with good yields (70-87%) and enantioselectivities (58-72%).
Chemoenzymatic synthesis of alpha(1)- and alpha-acetoxylated cyclic ketones
Tanyeli, Cihangir; Akhmedov, M (Elsevier BV, 2004-06-07)
alpha,beta-Unsaturated and saturated cyclic ketones were selectively oxidized at the alpha'- and alpha-positions using Mn(OAc)(3) and Pb(OAc)(4), respectively, resulting in high chemical yields. The resultant racemic alpha'- and alpha-acetoxylated substrates were resolved into corresponding enantiomerically enriched alpha'- and alpha-hydroxylated and acetoxylated compounds with 96-98% ee via PLE hydrolysis. The absolute configurations of alpha'-acetoxy-alpha,beta-unsaturated cyclic ketones were determined b...
Enantioselective synthesis of both enantiomers of 2-amino-2-(2-furyl)ethan-1-ol as a flexible building block for the preparation of serine and azasugars
Demir, Ayhan Sıtkı; Sesenoglu, O; Aksoy-Cam, H; Kaya, H; Aydogan, K (Elsevier BV, 2003-05-16)
The selective conversion of 1-(2-furyl)-2-hydroxyethan-1-one and ethyl 2-(2-furyl)-2-oxo acetate into (E)- and (Z)-oximes and oxime ethers followed by oxazaborolidine-catalyzed enantioselective reduction using different amino alcohols furnished both enantiomers of the important chiral building block 2-amino-2-(2-furyl)ethan-1-ol with an ee of up to 96%.
Citation Formats
A. S. Demir, N. T. Subasi, and E. Sahin, “Intermolecular one-pot cyclization of formyl-pyrroles of amino acid esters with norephedrine: stereoselective routes to new tricyclic pyrrole-pyrazine-oxazole fused structures,” TETRAHEDRON-ASYMMETRY, pp. 2625–2631, 2006, Accessed: 00, 2020. [Online]. Available: