The synthesis of enantiomerically pure, symmetrically substituted cyclopropane phosphonic acids — A constrained analog of the GABA antagonist phaclophen

Direct Catalytic Asymmetric Cyclopropylphosphonation Reactions of N,N-Dialkyl Groups of Aniline Derivatives by Ru(II)-Pheox Complex

Novel catalysis involving phosphonomethylation of N-methylaniline and asymmetric cyclopropylphosphonation reactions of N,N-diethylaniline derivatives with diazomethylphosphonates are reported. Optically active cyclopropylphosphonate derivatives were directly synthesized from diazomethylphosphonates and N,N-diethylaniline derivatives catalyzed by a Ru(II)-Pheox complex in one step in good yields and high diastereoselectivities (up to trans/ cis = > 99:1<) and enantioselectivities (up to 99% ee). D-labeling mechanistic studies of phosphonomethylation and cyclopropylphosphonation suggested that an enamine or iminium intermediate was generated in the reaction process.

Application of cyclic phosphonamide reagents in the total synthesis of natural products and biologically active molecules

A review of the synthesis of natural products and bioactive compounds adopting phosphonamide anion technology is presented highlighting the utility of phosphonamide reagents in stereocontrolled bond-forming reactions. Methodologies utilizing phosphonamide anions in asymmetric alkylations, Michael additions, olefinations, and cyclopropanations will be summarized, as well as an overview of the synthesis of the employed phosphonamide reagents.

Stereoselective Rh2(S-IBAZ)4-catalyzed cyclopropanation of alkenes, alkynes, and allenes: asymmetric synthesis of diacceptor cyclopropylphosphonates and alkylidenecyclopropanes

A mild and highly stereoselective rhodium(II)-catalyzed cyclopropanation of alkenes, alkynes, and allenes with diacceptor diazo compounds is reported. Using the phosphonate moiety as an efficient trans-directing group, the first catalytic asymmetric route to diacceptor cycloprop(en)ylphosphonates was developed by employing an α-cyano diazophosphonate and Rh(2)(S-IBAZ)(4) as chiral catalyst. The isosteric character of phosphonic and carboxylic acid derivatives allowed the alternative use of an α-cyano diazo ester in the process, leading to α-cyano cycloprop(en)ylcarboxylates in high yields and stereoselectivities. Taking advantage of the particular reactivity of the cyanocarbene intermediates involved in this system, the scope of compatible substrates could be extended to substituted allenes, leading to the development of the first catalytic enantioselective method for the synthesis of diacceptor alkylidenecyclopropanes.

Synthesis and preliminary pharmacological evaluation of the four stereoisomers of (2S)-2-(2'-phosphono-3'-phenylcyclopropyl)glycine, the first class of 3'-substituted trans C1'-2'-2-(2'-phosphonocyclopropyl)glycines

Four stereoisomers of (2S)-2-(2'-phosphono-3'-phenylcyclopropyl)glycine were synthesized by a stereocontrolled synthetic procedure and evaluated as mGluRs ligands. The (2S,1'R,2'S,3'R)-isomer (PPCG-2) showed to be a group III mGluRs selective ligand endowed with a moderate potency as mGluR4/mGluR6 agonist.

Catalytic asymmetric synthesis of cyclopropylphosphonates — Catalysts' scope and reactivity

The transition metal-catalyzed cyclopropanation of alkenes using α-diazomethylphosphonates leads to cyclopropylphosphonate derivatives in high yields. The reaction proceeds well with copper, rhodium, and ruthenium catalysts. The best catalysts for the enantioselective version are either Evans' Cu·bis(oxazoline) or Nishiyama's Ru·pybox.Key words: cyclopropylphosphonic acids, copper catalysts, ruthenium catalysts, cyclopropanation, diazo reagents.

Enantioselective Synthesis of Cyclopropylphosphonates Containing Quaternary Stereocenters Using a D2-Symmetric Chiral Catalyst Rh2(S-biTISP)2

[reaction: see text] Rh(2)(S-biTISP)(2)-catalyzed reactions of dimethyl aryldiazomethylphosphonates generate donor/acceptor-substituted rhodium carbenoid intermediates capable of cyclopropanation of styrenes in high yields (85-96%), diastereoselectivity (> or =98% de), and enantioselectivity (76-92% ee).

Asymmetric conjugate additions of chiral phosphonamide anions to alpha,beta-unsaturated carbonyl compounds. A versatile method for vicinally substituted chirons

Reactions of anions derived from chiral nonracemic allyl, crotyl, and cinnamyl bicyclic C(2)-symmetrical phosphonamides with alpha, beta-unsaturated cyclic ketones, esters, lactones, and lactams take place at the gamma-position of the reagents. The products are diastereomerically pure or enriched beta-substituted carbonyl compounds. The method also provides easy access to vicinal substitution of as many as three stereogenic centers including in some cases quaternary carbon atoms, in a one-pot sequence.

Asymmetric synthesis of functionalized carbocycles and heterocycles

Anions of 1-halo-4-hexenyl phosphonamides derived from chiral, enantiopure C2 symmetrical 1,2-diamino cyclohexane react at the gamma-position in conjugate addition reactions with alpha, beta-unsaturated carbonyl compounds such as cyclopentenone, 4-(H)-furanone, pyrroline-2-one, and cinnamates to give functionalized adducts. Addition to imines is also possible. The adducts can be transformed into enantiopure or enriched carbocyclic and heterocyclic compounds bearing useable functionality.

Lewis Acid-Promoted [2 + 1] Cycloaddition Reactions of a 1-Seleno-2-silylethene to 2-Phosphonoacrylates: Stereoselective Synthesis of a Novel Functionalized alpha-Aminocyclopropanephosphonic Acid

Stereoselective SnCl(4)-promoted [2 + 1] cycloaddition reactions of 1-seleno-2-silylethene 1 with 2-phosphonoacrylates 2 lead to highly functionalized cyclopropanephosphonate esters 3 in high yields. The cyclopropane products 3 are potentially versatile starting materials for biologically important compounds. Stereoselective synthesis of a novel functionalized alpha-aminophosphonic acid derivative, an analogue of (Z)-2,3-methanohomoserine 13, from the cycloadduct 3b was achieved. Stereoselectivity in the [2 + 1] cycloaddition was explained by consideration of the structure of the 2-SnCl(4) complex.