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A new method is described for the direct construction of synthetic genes by applying a modified version of the polymerase chain reaction (PCR) to crude oligonucleotide mixtures made by automated solid phase DNA synthesis. Construction of the HIV-1 393 bp rev gene and the 655 bp nef gene by this method is illustrated. The sequences for the entire top and bottom strands of rev were each programmed into an automated DNA synthesizer. Following DNA synthesis, the two crude oligonucleotide solutions were mixed together, specific primers were added, and the target gene was amplified by a modified PCR technique. Although the longer (greater than 200 bases) strands comprise a very small percentage of the total DNA after solid phase synthesis, this method uses PCR to 'find' and amplify such strands to create the target gene. The rev gene constructed by this method was found to contain 4 sequence errors, which were subsequently corrected by site-directed mutagenesis. In order to evaluate the source of sequence errors, several nef genes were made from the top and bottom strand DNA synthesis solutions using independent PCR's. Results suggest that sequence errors arose from both DNA synthesis and PCR. The utility of this method in producing a functional gene is demonstrated by expression of rev in E.coli.

The vinyl anions derived from 2,3-dihydrofuran, 2,3-dihydro-4fi-pyran, and ethoxyethene have been examined by carbon-13 FT NMR. The vinyl C-H coupling constants (V13c_ih) have been measured for the ethers and the anions. Observation of vinyl anions derived from vinyl ethers is readily accomplished with carbon-13 NMR.While all carbon resonances are shifted upon formation of the anion the most obvious effect is the large (56-61 ppm) downfield shift of the vinyl carbon bonded to lithium. In no case was allylic deprotonation observed under the reaction conditions.

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