Bis(hydroxymethylation) of the Active Methylene Group of 1,3-Dicarbonyl and Related Compounds
作者:Andrei Guzaev、Harri Lönnberg
DOI:10.1055/s-1997-1344
日期:1997.11
Treatment of dialkyl and di(aralkyl) malonates, alkyl cyano- and acetoacetates, and 1,3-diketones with formaldehyde in the presence of tertiary amines gives their 2,2-bis(hydroxymethyl) derivatives in 59 to 96% yield.
cis-Fused bicyclic acetals were obtained from the unusual cyclization reaction between diols and dihydropyran. Furothiopyran, substituted pyranopyrans, and pyranooxepine and pyranobenzoxepine compounds were obtained with high diastereoselectivity and cis-diastereomers were obtained in high yields.
Synthesis and stereochemistry of some dispiro-1,3-dioxanes with axial and helical chirality
作者:Ion Grosu、Sorin Mager、Gerard Plé、Eugen Mesaros
DOI:10.1016/0040-4020(96)00760-0
日期:1996.9
The stereoisomerism of some dispiro-1,3-dioxanes is discussed in terms of conformationalanalysis and axial and helical chirality. The influence of the flexibility of the rings on the representative number of isomers and on their NMRspectra is commented. For the 3,12-disubstituted-1,5,10,14-teraoxadispiro[5.2.5.2]hexadecane derivatives displaying a semiflexible structure two configurational diastereomers
The two isomers of 5-aminomethyltetrahydro-2H-pyran-2-carboxylic acid (9) and those of 5-aminomethyl-1, 4-dioxane-2-carboxylic acid (18) were synthesized from 2-ethoxycarbonyl-3, 4-dihydro-2H-pyran-5-carboxylic acid chloride (2) and dimethyl 1, 4-dioxane-2, 5-dicarboxylate (15), respectively. From the aminoacetal (19) and dimethyl bis (hydroxymethyl) malonate (21), trans-2-aminomethyl-1, 3-dioxane-5-carboxylic acid (26A) was synthesized. The configurations of these isomers were determined on the basis of their nuclear magnetic resonance spectra, and the preferred conformations of the isomers in aqueous solution were similarly deduced. No compound showed antiplasmin activity more potent than that of trans-4-aminomethylcyclohexanecarboxylic acid (1A).