A convenient method for the synthesis of α-silylacetic acids

A method is described for the preparation of α-silylacetic acids of the type R₃SiCH₂CO₂H by treating trimethylsilyl acetate with LDA followed by quenching with chlorosilanes.     

A convenient general method for the synthesis of hydroxy diacids

Olefinic aldehydes and epoxides with terminal double bonds react with Grignard reagents, and the acetates made from the resulting alcohols undergo double bond cleavage on treatment with RuCl₃·xH₂O in the presence of NaIO₄ to give acetoxy diacids. Hydrolysis with LiOH then affords hydroxy diacids.     

A convenient synthesis of phosphonothioic acids

A method for the convenient synthesis of phosphonothioates, or phosphonothioic acids, is reported. A significant advantage of the method is the alleviation of the need for purification of intermediates, other than washing with water. No chromatography is needed and the only purification step is the crystallization of the final product. The method uses standard reagents and should be applicable to the synthesis of phosphonothioic acids bearing a range of functional groups.     

A convenient method for the synthesis of roflumilast

A convenient synthetic method has been developed for the synthesis of roflumilast from 4-difluoromethoxy-3-hydroxybenzaldehyde and bromomethyl cyclopropane via O-alkylation, oxidation and N-acylation. With sodium hydroxide as alkali in the last step, the total yield of roflumilast can be up to 68.3 % and the purity of the target product reached 99.2 %. It was obvious that sodium hydroxide showed more economic advantage for scale-up production than sodium hydride or potassium tert-butoxide.     

A convenient, general synthesis of 1,1-dimethylallyl esters as protecting groups for carboxylic acids

[reaction: see text] Carboxylic acids were converted in high yield to their 1,1-dimethylallyl (DMA) esters in two steps. Palladium-catalyzed deprotection of DMA esters was shown to be compatible with tert-butyl, benzyl, and Fmoc protecting groups, and Fmoc deprotection could be carried out selectively in the presence of DMA esters. DMA esters were also shown to be resistant to nucleophilic attack, suggesting that they will serve as alternatives to tert-butyl esters when acidic deprotection conditions need to be avoided.     

A convenient synthesis of 2-chromonecarboxylic acids

Knoevenagel condensation of the β-ketosulfinyl intermediate II with butyl glyoxylate afforded the butyl 2-hydroxy-4-(2-hydroxyphenyl)-3-methylsulfinyl-4-oxobutyrates (III). Compounds III are versatile intermediates for the synthesis of either 2-chromonecarboxylates (V) or 2-carboxy-methylene-3-coumaranone esters (VII).     

Microwave irradiation: A facile,scalable and convenient method for synthesis of N-phthaloylamino acids

We describe herein a fast and rapid technique for preparation of N-phthaloyl amino acids under microwave irradiation. The microwave methodology is rapid, convenient, proceeds under mild conditions, and gives a better yield (81–98%) and high purity of the title compounds. The spectral data as well as the X-ray analysis established the structure of the prepared N-protected amino acids.     

A convenient method for 3-pyrroline synthesis

[reaction: see text]. The synthesis of a range of 3-pyrrolines has been achieved from primary amine starting materials using a two-step alkylation/alkylidene carbene CH-insertion reaction sequence. We have shown that insertion into a range of CH-bond types is possible, and the formation of nitrogen-bearing quaternary stereocenters is a relatively facile process. The insertion reaction occurs with >95% retention of stereochemistry, but the presence of protecting groups on nitrogen is generally deleterious to the cyclization process.     

A new convenient method for the synthesis of cardiolipin

A novel dichlorophosphate coupling method is developed for the synthesis of the title compound. O-Chlorophenyl dichlorophosphate can be used as a mild phosphorylating reagent to effectively couple with optically active 1,2-O-diacyl-sn-glycerol and 2-O-protected glycerol to assemble cardiolipin bearing different fatty acid chains.     

A convenient method for the synthesis of electron-rich phosphonates

Very electron-rich benzylic-type phosphonates can be prepared by treating the corresponding alcohols in triethyl phosphite with one equivalent of iodine at an appropriate temperature in a general one-pot process.     

A convenient method for the synthesis of substituted thioureas

A convenient method for the synthesis of substituted thioureas by the reaction of primary amines with molybdenum dialkyl dithiocarbamates has been developed. Primary amines on reaction with 0.5 equiv of molybdenum xanthate produce the corresponding thioureas in moderate to good yields in short times. Similar reactions with propargylamine or 2-aminoethanol produce cyclic thiaoxazolidine and oxazolidine derivatives, respectively.     

A convenient method for the synthesis of chlorocymantrene and bromocymantrene

Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2046–2047, November, 1994.     

A novel and convenient method for the synthesis of substituted naphthostyrils

3-Pyrrolyl-6-fluoro-naphthostyril 13 was synthesized via a base-catalyzed intramolecular cyclization of oxindole precursor 2 (Y=H). Derivatization of 2 (Y=I) through a one-pot reaction give 5-substituted naphthostyrils. This method allows convenient access to 3,5,6-trisubstituted naphthostyrils which may serve as a new template for CDK2 inhibition.     

A selective and convenient method for the synthesis of 2-phenylaminothiazolines

A series of 2-phenylaminothiazolines have been prepared from the corresponding N-(2-hydroxyethyl)-N'-phenylthioureas under mild reaction conditions using either thio-CDI (1,1'-thiocarbonyldiimidazole) or CDI (1,1'-carbonyldiimidazole) to promote the cyclization. This protocol provides the desired cyclization products in good yield with excellent selectivity. The scope and selectivity of this methodology are also described.     

A convenient method for the synthesis of N-hydroxyureas

Treatment of amines with 1-(4-nitrophenol)-N-(O-benzylhydroxy)carbamate yields the O-benzyl protected N-hydroxyureas. Hydrogenation of the O-benzyl protected N-hydroxyureas over 5% Pd/BaSO₄ cleanly gives the N-hydroxyureas in good yield. In addition to primary and secondary aliphatic and aromatic amines, this method converts amino sugars to the corresponding N-hydroxyureas without extensive protecting group chemistry.     

A convenient method for the synthesis of six-membered heterocyclic enaminones

Enaminones are widely employed in the synthesis of heterocycles, however heterocyclic enaminones and their use in the synthesis of more complex systems have been less studied. The reaction between 4-chloroacetylacetate and aliphatic or aromatic 1,2-aminoalcohols, 1,2-aminothiols or 1,2-diamines, yields in one pot a six-membered 1,4-heterocyclic system containing the enaminone moiety.