Lovro Selic

Regioselective 1,3-Dipolar Cycloadditions of (1Z)-1-(Arylmethylidene)-5,5-dimethyl-3-oxopyrazolidin-1-ium-2-ide Azomethine Imines to Acetylenic Dipolarophiles

The 5,5-dimethylpyrazolidin-3-one (4), prepared from ethyl 3-methylbut-2-enoate (3) and hydrazine hydrate, was treated with various substituted benzaldehydes 5a – i to give the corresponding (1Z)-1-(arylmethylidene)-5,5-dimethyl-3-oxopyrazolidin-1-ium-2-ide azomethine imines 6a – i. The 1,3-dipolar cycloaddition reactions of azomethine imines 6a – h with dimethyl acetylenedicarboxylate (=dimethyl but-2-ynedioate; 7) afforded the corresponding dimethyl pyrazolo[1,2-a]pyrazoledicarboxylates 8a – h, while by cycloaddition of 6 with methyl propiolate (=methyl prop-2-ynoate; 9), regioisomeric methyl pyrazolo[1,2-a]pyrazolemonocarboxylates 10 and 11 were obtained. The regioselectivity of cycloadditions of azomethine imines 6a – i with methyl propiolate (9) was influenced by the substituents on the aryl residue. Thus, azomethine imines 6a – e derived from benzaldehydes 5a – e with a single substituent or without a substituent at the ortho-positions in the aryl residue, led to mixtures of regioisomers 10a – e and 11a – e. Azomethine imines 6f – i derived from 2,6-disubstituted benzaldehydes 5f – i gave single regioisomers 10f – i.

A Simple Stereoselective Synthesis of Aplysinopsin Analogs

Simple and stereoselective syntheses of aplysinopsins and their analogs from either methyl 2-[(2,2-disubstituted ethenyl)amino]-3-(dimethylamino)prop-2-enoates 11 or 5-[(dimethylamino)methylidene]imidazolidine-2,4-diones 20 are described. The structures of products are established by 1H- and 13C-NMR, and NOESY spectroscopy, and X-ray crystal-structure analysis.

Dimethylamine substitution in N,N-dimethyl enamines. Synthesis of aplysinopsin analogues and 3-aminotetrahydrocoumarin derivatives

Abstract Some new six-membered aplysinopsin analogues were prepared from 5-dimethylaminomethylidene-2,4,6(1H,3H,5H)-pyrimidinetriones and indole derivatives. Also 2-[[(2,4,6-trioxohexahydropyrimidin-5-ylidene)methyl]amino]-3-dimethylaminopropenoates were synthesized and employed in the synthesis of fused 2H-pyran-2-ones.

A SIMPLE STEREOSELECTIVE ONE POT CONVERSION OF COMPOUNDS WITH A DIMETHYLAMINOMETHYLENE GROUP INTO ENOL ESTERS

A simple stereoselective synthesis of 2Z and 2Z,1′E alkyl 3-acyloxy-2-(2,2-disubstituted ethenyl) aminopropenoates 4 from alkyl 2-(2,2-disubstituted ethenyl)amino-3-dimethylaminopropenoates 1 in 12–91% yield is presented.