Acid anhydrides as alternatives to acid chlorides in the palladium‐catalyzed reaction with silacyclobutanes

The palladium‐catalyzed reaction of acid anhydrides with silacyclobutane gives a mixture of cyclic silyl enol ether, carboxy(propyl)silane, and 3‐(carboxysilyl)ketone. In the presence of N,N‐dicyclohexylcarbodiimido (DCC), the reaction preferentially provides a cyclic silyl enol ether in a good yield. In addition, the palladium‐catalyzed reaction of benzoic acid with silacyclobutane in the presence of two equivalents of DCC also affords a cyclic silyl enol ether in a moderate yield. Copyright © 2001 John Wiley & Sons, Ltd.     

Synthesis of a novel uracil-2,6-diaminopyridine-lithocholic acid conjugate that self-assembles into a cyclic dimer

Synthesis and self-association studies of a uracil-2,6-diaminopyridine-lithocholic acid conjugate are described. The dimeric supramolecular structure is characterized by NMR spectroscopic, ESI-MS, and size exclusion chromatographic studies.     

Regioselective Arene Functionalization: Simple Substitution of Carboxylate by Alkyl Groups

Arenes with various alkyl side‐chains were synthesized in high yields and excellent regioselectivities. Starting from toluic and naphthoic acids, the carboxylate group was conveniently substituted by alkyl halides by Birch reduction and subsequent decarbonylation. The method is characterized by inexpensive starting materials and reagents, and methylation of arenes was realized. Besides simple alkyl substituents, the scope of arene functionalization was extended by benzyl, fluoro, amino, and ester groups. We were able to control the alkylation of 1‐naphthoic acid during Birch reduction by the addition of tert‐butanol. This allowed the regioselective synthesis of mono and bis‐substituted naphthalenes from the same starting material.     

Gas chromatographic-mass spectroscopic identification of volatile oil constituents of Omphalocarpus procesum

Summary The steam volatile oil of the seeds ofOmphalocarpus procerum P. Beauv (Sapotaceae) was investigated by capillary gas chromatography with characterisation by mass spectroscopy. The identification of palmitic acid (8%), indole (2.6%), δ-cadinene (7%), cinnamic alcohol (2.12%), α-humulene (0.38%), γ-muurolene (0.49%) as well as smaller amounts of 25 additional compounds was confirmed by GC-MS. In all about 70 compounds were detected in the volatile oil which also contained a large fraction of oxygenated sesquiterpenes.     

Spectroscopic study of the keto-enol equilibrium of N-aryldiacetylthioacetamides and their reactivity

An NMR study of the equilibrium between keto-enol tautomeric forms of N-aryl-diacetylthioacetamides enables us to estimate their population ratio in solvents of increasing polarity. An X-ray analysis confirmed the structure of the thermodynamically most stable tautomer. We presume that the course of heterocyclization processes with N-aryldiacetylthioacetamides is affected by the structure of the reacting tautomeric form. The treatment of N-aryldiacetylthioacetamides with oxalyl or bromoacetyl bromides leads to thiazolidine derivatives. The reactivity of the 5-methylene group in the obtained thiazolidin-4-one derivatives was investigated. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 452–459, March 2008.     

Solvent‐free synthesis of α‐aminonitriles from aldehydes,amines and trimethylsilyl cyanide catalyzed by thallium(III) chloride tetrahydrate

A straightforward and efficient method has been developed for the synthesis of α‐aminonitriles by combining aldehydes, amines and trimethylsilyl cyanide in the presence of a catalytic amount of thallium(III) chloride tetrahydrate (1 mol%) under solvent‐free conditions at room temperature. Copyright © 2008 John Wiley & Sons, Ltd.