Angelina Georgieva

Acceleration of hetero-Michael reaction by symmetrical pentacyclic guanidines

Abstract Symmetrical pentacyclic guanidines 1a–c and 2 which contain the core skeleton of 13,14,15-isocrmbescidine 800, have been synthesized. In the presence of catalytic amounts of these guanidines 1, the reaction rate of the conjugate addition of pyrrolidine (9) to γ-crotonolactone (10) could be enhanced depending upon the size of the cavities and substituents on tetrahydropyran rings of 1 and 2.

Practical and Stereoselective Synthesis of a Pentacyclic Guanidine System: Synthetic Studies toward Ptilomycalin A and Related Compounds

Abstract Symmetrical pentacyclic guanidine compounds 3a – c have been synthesized based on the construction of 2,5-disubstituted pyrrolidines via sequential 1,3-dipolar cycloaddition and the formation of pentacyclic guanidine via guanylation followed by double N , O -acetalization. The present synthesis will provide a potential route for the synthesis towards ptilomycalin A ( 1 ) and 13,14,15-isocrambescidin 800 ( 2 ).

Cyclocondensations of homophthalic anhydrides with 1-aza-1,3-dienes

Abstract α,β-Unsaturated aldimines (1-aza-1,3-butadienes) 2, 4 and 7a-d react with homophthalic anhydrides 1a,b to give 3,4-dihydro-1(2H)-naphthalenone-4-carboxylic acids 3, 5, 8a-d (R2 = H) as main products. Homophthalic anhydride 1a and cinnamaldimine 7d gave rise to the diastereoisomeric naphthalenones 8d (R2 = H), along with the 3,4-dihydro-1(2H)-isoquinolinone-4-carboxylic acids 10 (R2 = H), and 3,4-dihydro-1(2H)-pyridinone 11 (R2 = H) as products of 3,4-, 1,2- and 1,4-addition to the 1-aza-1,3-butadiene, respectively. The effect of the reaction conditions on the ratio of adducts, produced by 1a and 7d, was studied. The structure and relative configurations of 3, 5, 8a-d, 10 and 11 were determined by NMR spectroscopy. In the case of cis-naphthalenone 8c and dihydropyridinone 11, the structure was confirmed by X-ray crystal structure analysis.

Reactions of α-chloroimines with homophthalic anhydrides. Synthesis and molecular structure of 3,3a-dihydrofuro[3,4-c] isoquinoline-1,5(4h,9bh)-diones, furo[3′, 4′:9,9α]-8,9,16,16a-tetrahydro-1h,3h,11h-dibenzo[a,g]quinolizine-1,11-diones and related compounds

Abstract The reaction of α-chloroimines 1 - 3 , resp. 11 with homophthalic anhydrides 4 leads to the formation of the isoguinoline ring system incorporated in furo[3,4-c]isoquinolinediones 8 - 10 , resp. 13a-(chloromethyl)-8H- dibenzo[a,g]-quinolizine-8-one-13-carboxylic acids 12 . The latter compounds were converted into furo[3′ 4′:9,9a]dibenzoquinolizinediones 13 under basic conditions. NMR studies provided information concerning the relative configuration and the solution conformation of the various heterocycles obtained. The molecular structure of 8b and 12b was determined by X-ray analysis.

Synthesis and Plant Growth Regulating Activity of New Triazolo- and Pyrazolopyrimidine Derivatives Of Aminomethyl, Aminoalkyloxymethyl Dimethylphosphine Oxides and (Aminomethane)Phosphonic Acid Esters

Abstract New triazolo[4,5-d]pyrimidine and pyrazolo[3,4-d]pyrimidine derivatives of aminomethyl-and aminomethyloxymethyl dimethylphosphine oxides 8–14 as well as of esters of (aminomethane) phosphonic acid 18–20 were synthesized. The structure of the compounds prepared was confirmed by means of elemend analysis, IR, 1H- and 31P(1H)-NMR spectroscopy. Tertiary phosphine oxides 8, 9 and 12 as well as phosphonate 20 showed herbicidal and plant growth regulating activity.

Synthesis of 11H-4b, 10b-dihydro [1] benzopyrano [4,3-c] isoquinoline-6,11 (5H)-diones and 13H-6c, 12b-dihydronaphtho [1′,2′:5,6]-pyrano [4-3c] isoquinoline-8,13 (7H)-dione from homophthalic anhydride and N-(2-hydroxyarylidene) alkylamines

Abstract 2-Alkyl-3-(2-hydroxyaryl)-3,4-dihydro-1(2H)-isoquinolinone-4-carboxylic acids (5,13) were prepared from homophthalic anhydride (1) and N-(2-hydroxyarylidene) alkylamines (2,10). The acids 5,13 showed a tendency towards cyclodehydration to give isoquinoline derivatives with fused [1] benzopyrane (8) or naphthopyrane (12) ring system. The relative configurations of the novel fused heterocyclic compounds 5,8,12,13 and related compounds were determined by NMR studies, and in the case of 13 also by means of X-ray analysis. Some MM2 force field molecular mechanics calculations on some selected fused heterocycles were executed. The naphtho [1′,2′:5,6] pyrano [4,3c]-isoquinoline ring system incorporated in the lactone 12 is hitherto unreported.

Effect of the Structure of 1-Aza-1,3-dienes on 1,2-versus 3,4-Selectivity in Cycloaddition Reactions withHomophthalic Anhydride†

The reaction of homophthalic anhydride 1 with N-(cinnamylidene)tritylamine 2a proceeds as a 3,4-cycloaddition to give 4-oxo-1,2,3,4-tetrahydronaphthalene-1-carboxylic acids 3, with N-(cinnamylidene)benzylamine 2b as a 1,2-cycloaddition with the predominant formation of a 1-oxo-1,2,3,4-tetrahydroisoquinoline-4-carboxylic acid, and with either 2a or cinnamaldehyde in the presence of Et 3 N with the formation of a 2-oxonaphtho[1,2-b]pyran-6-carboxylic acid.