Olefination of carbonyl compounds with gem-dizincioalkanes, bis(iodozincio)methane, 1,1-bis(iodozincio)ethane, and bis(bromozincio)methyltrimethylsilane, afforded the corresponding olefins in good to excellent yields.

About 40 years have passed since methylene dizinc reagent was discovered as a substitute for Wittig reagent. Density functional theory (DFT) calculations have been performed to understand the reaction pathways of methylenation of carbonyl compounds with bis(iodozincio)methane. The present computational/theoretical study concluded that the methylenation reaction with gem-dizinc reagent proceeds as a two-step reaction, that is, methylene addition (RDS) and olefination. In the first step, the nucleophilic attack of the CH2 group enhanced by two Zn proceeds under the assistance of the electrophilic activation of the carbonyl group with the Zn atom. In the second step, the olefination is facilitated by both Zn atoms of the gem-dizinc reagent without an electron transfer process.

SummaryImmunomodulation is a means to modulate an organism's function by antibody production to capture either endogenous or exogenous antigens. This method was applied to plants to repress the function of gibberellins (GAs), a class of phytohormones responsible for plant elongation, by anti-bioactive GA antibodies. Two different antibodies were produced in Arabidopsis as single-chain variable fragment (scFv) fused to green fluorescent protein (GFP) with four different subcellular localizations: endoplasmic reticulum (ER), cytosol, apoplastic space or the outer surface of the plasma membrane. When targeting scFv-GFP to ER, plants showed the highest accumulation of scFv-GFP, with binding activity, strong GFP fluorescence in ER-derived compartments and mild but clear GA-deficient phenotypes, including a smaller leaf size, delayed bolting, shorter inflorescence length and decreased germination. Plants expressing scFv-GFP in ER responded to exogenous GA 4 and contained 15-40 times greater endogenous GA 4 than wild-type plants. They also showed increased gene expression for GA3ox1 , GA20ox1 and GA20ox2 , but decreased expression for GA2ox1 , which are feedback and feedforward regulated by GA signalling, respectively. These results suggest that the level of free functional GA 4 decreased when trapped in the ER with scFv to the extent that mild GA-deficient phenotypes were created. A dramatic increase in the total sum of GA 4 (free plus scFv-GFP bound) was detected as a result of the up-regulation of GA biosynthesis (feedback regulated), and a decrease in GA 4 catabolism as a result of protection by scFv-GFP binding. This study demonstrates that the use of immunomodulation to inhibit the action of bioactive GAs is an effective method of creating GA-deficient plants.