Convenient synthesis of optically active α‐hydroxyphosphinic acids

The reaction of O‐menthyl phenylphosphonite 1 with aromatic aldehydes in the presence of Me₃SiCl provided the O‐menthyl α‐hydroxyphosphinates 2 . Acidic hydrolysis of 2 gave the corresponding α‐hydroxyphosphinic acids 3 . The (+)‐enantiomer of 3a and 3b , adduct of benzaldehyde and 4‐methylbenzaldehyde respectively, were obtained via multiple recrystallization. The absolute configuration of (+)‐ 3a was determined as S by X‐ray crystallography. © 2003 Wiley Periodicals, Inc. Heteroatom Chem 14:312–315, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10150     

The first stereoselective synthesis of optically active thiosulfinates

Treatment of optically active $\text{p}$-toluenesulfinamides (1) with thiols (2) in the presence of trifluoroacetic acid was found to give optically active $\text{p}$-toluenethio-sulfinates (3) with predominant inversion of configuration. Stereospecificity of this reaction varies from 30 to 80%. Some mechanistic aspects of the reaction are also discussed.     

The synthesis of optically active P‐heterocycles

Optically active 1‐alkoxy‐ and 1‐amino‐3‐phospholene oxides were synthesized by the reaction of the corresponding 1‐chloro‐3‐phospholene oxides with (1R,2S,5R)‐(–)menthol and (S)‐(–)‐α‐phenylethylamine. The 3‐methyl‐3‐phospholene oxides were subjected to dichlorocyclopropanation under liquid–liquid phase transfer catalytic conditions to afford the 3‐phosphabicyclo[3.1.0]hexane 3‐oxides as a mixture of four diastereomers. Thermolysis of the menthyl‐phosphabicyclohexane oxides led to the corresponding 1,2‐dihydrophosphinine oxide as a diastereomeric mixture of two double‐bond isomers. As a result of additional steps, the dichlorocarbene addition reaction of the 1‐menthyl‐3,4‐dimethyl‐3‐phospholene oxide resulted in eventually, the formation of a 4‐dichloromethylene‐1,4‐dihydrophosphinine oxide. © 2010 Wiley Periodicals, Inc. Heteroatom Chem 21:271–277, 2010; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20599     

Regiospecific synthesis of trichloromethyl substituted 4,5‐dihydro‐1h‐1‐tosylpyrazoles

The regiospecific synthesis of a new series of eight 3‐alkyl(aryl)‐5‐hydroxy‐5‐trichloromethyl‐4,5‐dihydro‐1H‐1‐tosylpyrazoles is reported. The 1‐p‐tosyl‐2‐pyrazolines were obtained from the cyclocondensation reaction of 4‐alkyl(aryl)‐4‐alkoxy‐1,1,1‐trichloroalk‐3‐en‐2‐ones, [where alkyl = H, Me and aryl = ‐C₆H₅, 4‐CH₃C₆H₄, 4‐OCH₃C₆H₄, 4‐FC₆H₄, 4‐ClC₆H₄, 4‐BrC₆H₄,] with p‐tosylhydrazine in 64 to 92 % yields, employing anhydrous toluene at reflux or diethyl ether at room temperature as the reaction condition.     

Synthesis of 1‐nonanoyl/octadecanoyl‐4‐substituted thiosemicarbazides and substituted 1,2,4‐trizoles as biological active compounds

4‐Alkyl/aryl‐5‐nonanoyl/octadecanoyl‐2,4‐dihydro‐3H‐1,2,4‐triazoline‐3‐thiones were synthesized as potential antimicrobial agents. The course of synthesis included the reaction of nonanoyl/octadecanoyl hydrazines with selected alkyl/aryl isothiocyanates. The prepared thiosemicarbazides gave by cyclization the required 1,2,4‐triazoles. A number of synthesized compounds were subjected to in vitro testing against two gram‐positive, two gram‐negative bacteria and two fungi.     

Convenient synthesis of N‐substituted 1‐alkyl and 1‐aryl‐3‐aminoisoquinolines

Cyclocondensation of 2‐acylphenylacetonitriles 1 with amines affords 1‐substituted 3‐aminoisoquinolines 2 in good yields.     

Synthesis of optically active N‐protected α‐aminoketones and α‐amino alcohols

A series of optically active N‐protected α‐aminoketones were synthesized via the Grignard reaction of the Weinreb amides of the N‐tert‐butoxycarbonyl amino acids. Reduction of the α‐aminoketones by sodium borohydride resulted in the corresponding 1,2‐amino alcohols. © 2003 Wiley Periodicals, Inc. Heteroatom Chem 14:603–606, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10195     

Design and synthesis of optically active 2‐phenylimidazolecarboxamides featuring amino acid motive

Overall sixteen new, optically active carboxamides 1‐3 have been synthesized. These compounds based on the 2‐phenylimidazole and featuring amino acid residues are linked on the 4‐position by an amidic bond. Two general methods were used for their construction. Whereas the first method employs acylchlorides as a reactive species, the second one involves a condensation of mixed anhydrides with the amino acid counterparts. Actually, the second method proved to be more efficient than the first one. Carboxamides 1‐3 were preliminarily tested as N‐chelating ligands with an application in the Henry or Aldol reactions affording either poor yields or enantiomeric excesses.     

α‐Propargyl amino acid‐derived optically active novel substituted polyacetylenes: Synthesis,secondary structures,and responsiveness to ions

Novel optically active substituted acetylenes HC? CCH₂CR¹(CO₂CH₃)NHR² [(S)‐/(R)‐ 1 : R¹ = H, R² = Boc, (S)‐ 2 : R¹ = CH₃, R² = Boc, (S)‐ 3 : R¹ = H, R² = Fmoc, (S)‐ 4 : R¹ = CH₃, R² = Fmoc (Boc = tert‐butoxycarbonyl, Fmoc = 9‐fluorenylmethoxycarbonyl)] were synthesized from α‐propargylglycine and α‐propargylalanine, and polymerized with a rhodium catalyst to provide the polymers with number‐average molecular weights of 2400–38,900 in good yields. Polarimetric, circular dichroism (CD), and UV–vis spectroscopic analyses indicated that poly[(S)‐ 1 ], poly[(R)‐ 1 ], and poly[(S)‐ 4 ] formed predominantly one‐handed helical structures both in polar and nonpolar solvents. Poly[(S)‐ 1a ] carrying unprotected carboxy groups was obtained by alkaline hydrolysis of poly[(S)‐ 1 ], and poly[(S)‐ 4b ] carrying unprotected amino groups was obtained by removal of Fmoc groups of poly[(S)‐ 4 ] using piperidine. Poly[(S)‐ 1a ] and poly[(S)‐ 4b ] also exhibited clear CD signals, which were different from those of the precursors, poly[(S)‐ 1 ] and poly[(S)‐ 4 ]. The solution‐state IR measurement revealed the presence of intramolecular hydrogen bonding between the carbamate groups of poly[(S)‐ 1 ] and poly[(S)‐ 1a ]. The plus CD signal of poly[(S)‐ 1a ] turned into minus one on addition of alkali hydroxides and tetrabutylammonium fluoride, accompanying the red‐shift of λ_max. The degree of λ_max shift became large as the size of cation of the additive. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

A novel synthesis of 1‐substituted 2H‐isoquinolin‐3‐ones

The intramolecular cyclization of 2‐acylphenylacetonitriles 1 under strongly acidic conditions easily affords 1‐substituted 2H‐isoquinolin‐3‐ones 2 in excellent yields.     

Studies with 1‐functionally substituted alkyl azoles: Novel synthesis of functionally substituted azolylbenzimidazoles and functionally substituted azolyl‐1,2,4‐triazoles

ω‐Azolylacetophenones 1 and 2 react with dimethylformamide dimethylacetal to yield enaminones 7,8 that were converted into azolylazoles via reaction with hydrazine and with hydroxylamine. Compounds 1,2 also coupled with aromatic diazonium salts to yield arylhydrazones and reacted with nitrous acid to yield corresponding oximes.     

Facile synthesis of various substituted taurines,especially syn- and anti-1,2-disubstituted taurines,from nitroolefins

Taurine and substituted taurines present a group of important structural elements in many natural products. Various substituted taurines, including 1- and 2-substituted, 1,1-, syn-1,2-, and anti-1,2-disubstituted taurines, were synthesized from the corresponding nitroolefins via Michael addition with thioacetic acid, oxidation with peroxyformic acid, and the catalytic hydrogenation under the catalysis of palladium on carbon or platinum dioxide. It is a general, versatile, and salt-free method for the preparation of substituted taurines, especially for syn- and anti-1,2-disubstituted taurines and some taurines with more bulky substituents. The stereostructures of both syn- and anti-1,2-disubstituted taurines were deduced from the nitroalkyl thioacetates in the Michael addition, which were identified via the Karplus equation analysis and computational analysis, and finally confirmed by the XRD single crystal analysis. The diastereoselectivity in the Michael addition was rationalized with the Cram rule.     

Facile synthesis of 4‐substituted 3,4‐dihydro‐1H‐2,1,3‐benzothiadiazine 2,2‐dioxides

A new method for the preparation of 4‐substituted 3,4‐dihydro‐1H‐2,1,3‐benzothiadiazine 2,2‐dioxides is described. Treatment of t‐butyl N‐phenylsulfamoylcarbamate derivatives ( 1 ) with different aldehydes afforded the corresponding intramolecular cyclized products 2 under trifluoroacetic acid conditions. © 2011 Wiley Periodicals, Inc. Heteroatom Chem 22:192–197, 2011; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.20670     

The synthesis of 1‐[(substituted)pyrazol‐5‐yl]‐iminomethyl‐2‐nitroiminoimidazolidine and its derivatives

In this article 1‐[(substituted)pyrazol‐5‐yl]iminomethyl‐2‐nitroimino imidazolidines ( II ) and their derivatives were synthesized. All the compounds were verified by elemental analysis, ¹H NMR and IR. In the reaction of II with halides, two different results were observed.     

A facile synthesis of substituted 3‐amino‐1H‐quinazoline‐2,4‐diones

A new synthesis of a series of 3‐amino‐1H‐quinazoline‐2,4‐diones is described. The 1H‐quinazoline‐2,4‐dione 10 was made starting with fluorobenzoic acid in three high yielding steps. The key step of this synthesis involved the generation of the dianion of urea 7 and the subsequent intramolecular nucleophilic displacement of the 2‐fluoro to form the quinazolinedione ring. The 3‐amino moiety was incorporated using (2,4‐dinitro‐phenyl)‐hydroxylamine as the aminating reagent.     

Efficient synthesis of taurine and structurally diverse substituted taurines from aziridines

Taurine and substituted taurines were synthesized efficiently from aziridines via ring-opening reaction with thioacetic acid, oxidation with performic acid, and hydrolysis in hydrochloric acid. The current method shows more benefit in purification and efficiency in the preparation of taurine and structurally diverse 2-substituted, 2,2-disubstituted, and 1,2-, 2,2-, and 2,N-alkylene taurines.     

A tolan substituted optically active spiropyran

A substituted optically active spiropyran with a tolan group in the 6′-position is described. Both the parent spiropyran and its derivative were separated by chiral HPLC and characterized by CD spectroscopy. There is a ‘diastereomeric switch’ at temperatures below −30°C , but the compound does not show liquid crystalline properties.     

Regiospecific synthesis of 2‐substituted furanonaphthoquinones

The naturally‐occurring furanonaphthoquinones 1a‐d have been synthesized from 3‐furancarboxylic acid and 2,3‐dimethoxybenzaldehyde via the Birch reduction‐elimination.     

Iodine catalyzed synthesis of α,α'‐bis(substituted benzylidene)‐1‐carbethoxy‐4‐piperidone

A facile and efficient method for the preparation of α,α′‐bis(substituted benzylidene)‐1‐carbethoxy‐4‐piperidone is described using iodine as a catalyst in acetonitrile. The reaction proceeds rapidly at room temperature, giving high yields of products.