A simple protocol for the synthesis of α-substituted phosphonates

An efficient, easy-to-handle, and mild substitution reaction approach has been developed for the synthesis of phosphonate derivatives, which are very important in the field of industrial, agricultural, and medicinal chemistry. A large number of nucleophiles, including arylamines, alkylamines, heteroarylamines, primary amines and secondary amines, sulfides, and carbides were attempted to react with α-tosyloxyphosphonate 1. The reaction proceeded under catalyst-free and neat conditions and the corresponding phosphonates 2 were afforded in good yields.     

Catalytic asymmetric one-pot synthesis of α-methylene-γ-lactams

An organocatalytic enantioselective synthesis of α-methylene-γ-lactams has been developed. The reaction between protected 2-aminomalonates and Morita–Baylis–Hillman carbonates is catalyzed by chiral Lewis bases to afford the corresponding lactams in excellent yields and moderate to good enantioselectivities, after work-up.     

A facile synthesis of bicyclic α-methylene-γ-lactones by intramolecular cyclization of allylsilylated aldehydes

Bicyclic α-methylene-γ-lactones were synthesized employing intramolecular reaction of an aldehyde unit with a β-ethoxycarbonylallylsilane function by the action of TiCl₄ in an excellent yield.     

The hydrocyanation route to β- and γ-amino acids. A synthesis of α-methylene-β-alanine

Hydrocyanation of several phthalimidoalkynes proceeds with good regioselection yielding products which were easily converted into unsaturated and saturated β- and γ-amino acids.     

A convenient synthesis and cytotoxic evaluation of N-unsubstituted α-methylene-γ-lactams

Chemoselective reduction of 3-aryl-2-diethoxyphosphoryl-4-nitroalkanoates provided the corresponding α-diethoxyphosphoryl-γ-lactams in completely diastereoselective manner. The products were shown to be useful substrates for the synthesis of mono-β-substituted and β,γ-disubstituted α-methylene-γ-lactams. Cytotoxicity of these compounds was evaluated.     

First synthesis of dialkyl phosphonate derivatives of sesquiterpene α-methylene-γ-lactone

The stereoselective synthesis of two phosphorus-containing derivatives of the known guaianolide arglabin was carried out for the first time. The molecular structures of these products were established based on the spectroscopic data and the results of X-ray diffraction analysis of one of these compounds.     

Regiospecific synthesis of α-methylene-β-lactams by a homogeneous palladium catalyzed ring expansion-carbonylation reaction

Tetrakis(triphenylphosphine)palladium(O) [or palladium acetate and added triphenylphosphine] catalyzes the carbonylation of methyleneaziridines to _α-methylene-_β-lactams at room temperature and one atmosphere.     

A simple approach for the synthesis of new pyrimidinyl α-amino acids

A simple synthetic method for the preparation of optically active pyrimidinyl α-amino acids is presented. A nucleophilic ipso-substitution reaction between 2-(benzylsulfonyl)-4-isopropoxypyrimidines and a nucleophilic side chain of several protected natural α-amino acids is investigated to obtain new pyrimidin-2-yl α-amino acids. A detailed optimisation study of this reaction is discussed. Moreover, the selective O-alkylation of 2-(benzylsulfanyl)-4(3H)pyrimidinones with a hydroxylic side chain of some natural α-amino acids under Mitsunobu conditions is studied as a method to prepare new pyrimidin-4-yl α-aminoesters.     

One-pot synthesis of chiral α-methylene-γ-lactams with excellent diastereoselectivities and enantioselectivities

An efficient one-pot asymmetric synthesis of highly substituted γ-lactams containing α-methylene groups has been successfully developed. A wide range of γ-lactams could be obtained in high yields with excellent diastereomeric ratios of up to 99:1 in favor of trans isomers. In particular, excellent enantioselectivities of the two newly formed stereogenic centers with up to 99% ee were observed.     

Asymmetric Baylis–Hillman reaction using sugar acrylates—synthesis of optically active α-methylene-β-hydroxy alkanoates

A study on the asymmetric Baylis–Hillman reaction of three chiral acrylates; 1,2:5,6-di-O-iso-propylidine-α-d-glucofuranose-3-acrylate 1, 2,3:5,6-di-O-iso-propylidine-α-d-mannofuranose-1-acrylate 2 and 1,2-O-iso-propylidine-5-O-tert-butyldimethylsilyl-α-d-xylofuranose-3-acrylate 3, with various aldehydes was conducted, resulting in adducts with moderate diastereoselectivity (5–40% e.e.).     

A simple and efficient stereoselective synthesis of (−)-cleistenolide

A simple and straightforward stereoselective synthesis of α,β-unsaturated δ-lactone, (?)-cleistenolide has been accomplished in 10 steps in an overall yield of 19%, starting from inexpensive and commercially available starting materials, respectively. This linear synthesis utilizes Sharpless asymmetric dihydroxylation, sulfur ylide mediated epoxide opening followed by ring-closing metathesis (RCM) for the formation of six-membered lactone ring as the key step sequence.