Karolina Janikowska

TMSCl as a Rate-Accelerating Additive in Acylations of Amines with 5-(α-Amino-α′-hydroxy)methylene Meldrum Acids

Abstract Aspects are presented of the acylation of amines, alcohols, and thiols with 5-(α-amino-α′-hydroxy)methylene Meldrum acids. We placed special emphasis on the acylation reaction of secondary amines with 5-(α-amino-α′-hydroxy)methylene Meldrum acids, which, because of their basicity, caused problems concerning salt formation with a Meldrum acid derivative. We found that secondary amines, which react at the slowest rate and give a poor yield with 5-(α-amino-α′-hydroxy)methylene Meldrums acid, react quickly and with high yields with the same reagent in the presence 1 to 3 equivalents of TMSCl. Acylation with this derivative of Meldrum acid was optimized for such factors as reaction temperature, solvent polarity, and acidity of the environment. We have prepared a wide range of nonsymmetrical malononic acid diamids, esters, and thioesters of malonamic acid. GRAPHICAL ABSTRACT

One-Step Synthesis of β-Lactamswith Retro-Amide Side Chain

A one-pot synthesis for the preparation of 1,4-disubstituted 2-oxoazetidine-3-carboxylic acid amides was developed. 5-[(N-substituted-amino)(hydroxy)methylene] Meldrums acids act as a source ofketenes that react with aldimines in boiling toluene to give β-lactams with a retro-amide side chain.

Simple Method for the Preparation of Dialkyl (2,3-Dihydro-1,3-thiazol-2-YL)-phosphonates

Abstract A simple synthesis of dialkyl (2,3-dihydro-1,3-thiazol-2-yl)-phosphonates from thiazolium salts and trialkyl phosphites is described. The series of dialkyl (2,3-dihydro-1,3-thiazol-2-yl)-phosphonates with various substituents in positions 3, 4, and 5 of the thiazole ring were prepared. However, only phosphonates with an aryl on the nitrogen atom were stable enough for chromatographic purification, although all the new phosphonates are very sensitive to oxidation. We made efforts to apply dialkyl (2,3-dihydro-1,3-thiazol-2-yl)-phosphonates in a Horner–Wadsworth–Emmons reaction, but the generated antiaromatic anion of phosphonate decomposed quickly, even at −70°C. GRAPHICAL ABSTRACT

New thiourea organocatalysts and their application for the synthesis of 5-(1H-indol-3-yl)methyl-2,2-dimethyl-1,3-dioxane-4,6-diones a source of chiral 3-indoylmethyl ketenes

ABSTRACT The stereoselective properties of modified thiourea organocatalysts were tested in the Friedel–Crafts alkylation of indole with 5-arylidene-2,2-dimethyl-1,3-dioxane-4,6-diones, which produces chiral 5-((1H-indol-3-yl)(aryl)methyl)-2,2-dimethyl-1,3-dioxane-4,6-diones. Based on a tentative reaction mechanism for ((S)-N-benzyl-2-(3-(3,5-bis(trifluoromethyl)phenyl)thioureido)-N,3,3-trimethylbutanamide organocatalysts, modifications were applied in four selected regions. Systematic structure-stereoselectivity relationship study allowed designing the best efficient organocatalyst for the investigated Friedel–Crafts alkylation of indole with 5-arylidene-2,2-dimethyl-1,3-dioxane-4,6-diones. GRAPHICAL ABSTRACT