From acyclic to cyclic α-amino vinylphosphonates by using ring-closing metathesis.

Acyclic α-amino vinylphosphonates were alkylated through the Mitsunobu reaction then diolefinic compounds hence formed were subjected to RCM. Studies on the scope and limitations of RCM with these sterically hindered α-amino vinylphosphonates are detailed.

Cerium(IV) ammonium nitrate mediated 5-endo-dig cyclization of α-amino allenylphosphonates to spirodienones.

α-Amino allenylphosphonates were treated with cerium(iv) ammonium nitrate under various conditions to form spirodienones in good to excellent yields. The 5-endo-dig cyclization proceeds through the formation of a key iminium intermediate. A comprehensive study on the nature of the solvent used for this reaction was undertaken resulting in the formation of three types of spirodienone scaffolds.

1-Aminocyclopropane-1-carboxylic acid oxidase: insight into cofactor binding from experimental and theoretical studies.

1-Aminocyclopropane-1-carboxylic acid oxidase (ACCO) is a nonheme Fe(II)-containing enzyme that is related to the 2-oxoglutarate-dependent dioxygenase family. The binding of substrates/cofactors to tomato ACCO was investigated through kinetics, tryptophan fluorescence quenching, and modeling studies. α-Aminophosphonate analogs of the substrate (1-aminocyclopropane-1-carboxylic acid, ACC), 1-aminocyclopropane-1-phosphonic acid (ACP) and (1-amino-1-methyl)ethylphosphonic acid (AMEP), were found to be competitive inhibitors versus both ACC and bicarbonate (HCO(3)(-)) ions.

[2,3]-Sigmatropic rearrangement of ynamides: preparation of α-amino allenephosphonates.

α-Amino allenephosphonates were easily prepared in two steps from protected amines, propargyl alcohols, and chlorophosphites. First, ynamides were synthesized from unprotected 1-bromopropargyl alcohols using a copper(II) catalyzed coupling reaction. In the second step, the previously prepared ynamides were transformed directly to allenes through a [2,3]-sigmatropic rearrangement of propargyl phosphites.

An efficient synthesis of enantiomerically pure (R)-pipecolic acid, (S)-proline, and their N-alkylated derivatives.

Enantiomerically pure (R)-(+)-pipecolic acid was synthesized in four steps and 42% overall yield starting from dihydropyran and (R)-alpha-methylbenzylamine. A general short strategy is also described for preparing (S)-proline (47.5% overall yield) and derivatives.