Diethyl (fluorocarbethoxymethyl)phosphonate (1), prepared from triethyl phosphite and ethyl bromofluoroacetate, reacts with n-butyllithium in THF to give the phosphonate carbanion 2.Addition of the pregenerated carbanion 2 to a THF solution of methyl or ethyl oxalyl chloride at -78 °C forms the acylated phosphonate (Et0)2P(0)CF(C0C02R)CC>2Et (3). In situ reaction of 3 with Grignard reagents affords a-fluoro-a,/3-unsaturated diesters R'(C02R)C=CFC02Et in moderate to good yields with high E-stereoselectivity. The reaction is applicable to primary, secondary, and tertiary alkyl, alkenyl, alkynyl, aryl, cyclohexyl, and perfluorinated Grignard reagents. The assignment of E and Z configuration is based on NOE experiment. The E/Z ratio of unsaturated diesters formed in the reaction varies with the metal ion and cosolvent. However, solvents and bases have little influence on the stereoselectivity.1:1 mixture of ethylenic triethyl esters (Et02CCFH)(C02-Et)C=CHC02Et and the isomerization product (Et02-CCH2)(C02Et)C=CFC02Et.8 Alkylation of (ethylphenyl)t Chung Cheng Institute of Technology.

Nineteen biscoumarins bearing free and modified hydroxyl substituents at benzoyloxyphenyl linker have been synthesized by multiple step synthesis. Among these biscoumarins, thirteen were found to be active molecules against HIV-1 integrase (HIV-1 IN). The structure-activity relationship of the nineteen compounds on HIV IN may be useful for the design of potent therapeutic agents.

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4-Nitrophenyl-N-substituted carbamates (1) are characterized as pseudosubstrate inhibitors of acetylcholinesterase. The first step is formation of the enzyme-inhibitor tetrahedral intermediate with the inhibition constant (Ki), the second step is formation of the carbamyl enzyme with the carbamylation constant (kc), and the third step is hydrolysis of the carbamyl enzyme with decarbamylation constant (kd). According to pre-steady state kinetics the Ki step is divided further into two steps: (1) formation of the enzyme-inhibitor complex with the dissociation constant (KS) and (2) formation of the enzyme-inhibitor tetrahedral intermediate from the complex with the equilibrium constant (k2/k-2). Since the inhibitors are protonated in pH 7.0 buffer solution, the virtual dissociation constant (KS') of the enzyme-protonated inhibitor complex can be calculated from the equation, -log KS'=-log KS-pKa + 14. The -logKS, -log KS', log k2, and log k-2 values are multiply linearly correlated with the Jave equation (log(k/k0)=rho*sigma* + deltaEs + psi pi). For -log KS'-sigma*-Es)pi-correlation, the rho* value of -0.4 indicates that the enzyme-protonated inhibitor complexes have more positive charges than the protonated inhibitors, the delta value of 0.44 suggests that the bulkily substituted inhibitors lessen the reaction due to the difficulty of the inhibitors to enter the narrow enzyme active site gorge, and the psi value of 0.27 implies that the inhibitors with hydrophobic substituents accelerate the inhibitors entering the active site gorge of the enzyme. For log k2/k-2,-sigma*-Es-pi-correlation, the rho* value of 1.1 indicates that the enzyme-protonated inhibitor tetrahedral intermediates have more negative charges than the enzyme-protonated inhibitor complexes, the delta value of 0.15 suggests that the bulkily substituted inhibitors are difficult to bind into a small acyl binding site of the enzyme, and the psi value of -0.3 implies that the inhibitors with hydrophobic substituents resist binding to the hydrophilic acyl binding site of the enzyme.

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