RESUMO
Readily available N-acylbenzotriazoles 2a-q efficiently acylate aqueous ammonia and primary and secondary amines to give primary, secondary, and tertiary amides in good to excellent yields. The wide applicability of the procedure is illustrated by the preparation of (i) alpha-hydroxyamides from alpha-hydroxy acids and of (ii) perfluoroalkylated amides.
RESUMO
One-carbon homologation of carboxylic acids is achieved by (i) treatment of an acyl chloride with 1-[(trimethylsilyl)methyl]-1H-1,2, 3-benzotriazole (BtCH(2)TMS) (1) to afford N-(acylmethyl)benzotriazoles 3a-f, followed by (ii) conversion of 3a-f with triflic anhydride into RC(OTf)=CHBt 4a-f, and (iii) the subsequent reaction of 4a-c with NaOCH(3) followed by 1N HCl to afford esters RCH(2)CO(2)R' 7a-c in overall yields of 50-70%. For the aliphatic compounds 5d-f, treatment of 5d-f with p-toluenesulfonic acid followed by TBAF/THF afforded acids RCH(2)COOH 7d-f.
RESUMO
The novel three-carbon synthon 1-(1H-1,2, 3-benzotriazol-1-yl)-3-chloroacetone for the synthesis of benzothiazoles, pyrido[1,2-a]indoles, and styryl-substituted indolizines and imidazo[1,2-a]pyridines is reported. The proposed routes are a general and efficient approach for heterocyclizations followed by benzannelations or attachment of arylethenyl pharmacophores.
RESUMO
A variety of functionalized N-allylamines and N-allylsulfonamides are synthesized by Pd(II)-catalyzed intermolecular amination of the corresponding N-allylbenzotriazoles.
RESUMO
N-Acylbenzotriazoles react with aryl isocyanates to form, depending on the type of acyl group, compounds based on five different classes of polycyclic heteroaromatics. Higher alkanoyl-, acetyl-, acetoacetyl-, aroyl-, and cinnamoylbenzotriazoles yield, respectively, derivatives of quinoline, pyrimidino[5,4-c]quinoline, benzo[b]-1,8-naphthyridine, phenanthridine, and indolo[2, 3-b]quinoline by incorporating 3, 3, 4, 2, and 2 molecules, respectively, of the isocyanate per acylbenzotriazole molecule.
RESUMO
Numerous 1,2-diaryl(heteroaryl)pyrroles and -3-methylpyrroles were prepared in a two-step procedure from N-allylbenzotriazoles via intramolecular oxidative cyclization in the presence of Pd(II) catalyst.
RESUMO
1-Acylbenzotriazoles 1 are efficient C-acylation reagents for the regioselective conversion of ketone enolates 2 into beta-diketones 3.
RESUMO
A general empirical relationship has been developed for estimating the cloud point of pure nonionic surfactants of the alkyl ethoxylate class. For a set of 62 structures, composed of linear alkyl, branched alkyl, cyclic alkyl, and alkylphenyl ethoxylates, cloud points can be estimated to an accuracy of ±6.3°C (3.7°C median error) using the logarithm of the number of ethylene oxide residues and three topological descriptors that account for hydrophobic domain variation. Copyright 1997Academic Press
RESUMO
Relationships between the molecular structure and the critical micelle concentration (cmc) of anionic surfactants were investigated using a quantitative structure-property relationship approach. Measured cmc values for 119 anionic structures, representing sodium alkyl sulfates and sodium sulfonates with a wide variety of hydrophobic and hydrophilic structures, were considered. The best multiple linear regression model involved three terms (descriptors) and had a correlation coefficient of R2 = 0.940. Very good correlations (R2 = 0.988) were obtained using three descriptors for a subset of 68 structures, with structural variation only in the hydrophobic domain. From the descriptors used in these regressions, one can conclude that the cmc is primarily dependent on the size (volume or surface area) of the hydrophobic domain and to a lesser extent on the structural complexity of the surfactant molecule.
