Ming-Yi Chen

Free radical type addition of toluenesulfonyl cyanide to unsaturated hydrocarbons

Abstract By catalysis of AIBN, tosyl cyanide adds in a regio- and stereoselective manner to unsaturated hydrocarbons, including alkenes, dienes and 1-hexyne. Accompanied intramolecular cyclization and ring cleavage were effected in reactions with norbornadiene, 1,5-cyclooctadiene and pinenes.

Reaction of dithio-substituted cinnamyllithium with carbonyl compounds: a test of the HSAB principle

Abstract By mediation of BF 3 .Et 2 O , dithio-substituted cinnamyllithium 2 reacted predominantly at the α-site with carbonyl compounds. No selectivity was found when the reaction was performed in the absence of BF 3 .Et 2 O .

Boron trifluoride promoted reaction of dithio-substituted allylic anions and cyclic ethers

Abstract Allylic anions generated from 2-propenyl-1,3-dithiane and 2-styryl-1,3-dithiane react exclusively at α-carbons with three- to six-membered cyclic ethers in the presence of BF 3 . Et 2 O .

Samarium diiodide-mediated asymmetric reactions of 8-phenylmenthyl esters

Abstract (−)-8-Phenylmenthol was used as a chiral auxiliary to direct asymmetric reactions of its preformed carboxylates. Reduction of xanthates 1a and 1b by SmI 2 likely proceeded via HMPA-bound samarium enolate intermediates. Self- and cross-pinacolic coupling reactions of 8-phenylmenthyl α-oxoesters were achieved in a highly stereoselective manner by treatment with SmI 2 at −78°C. The stereochemical outcome was consistent with a chelated mode of transition states.

Stereogenic reactions of the α-carbon radicals of 8-phenylmenthyl esters

The stereoselective free-radical type reduction and cyclisation of 8-phenylmenthyl esters is described; the predominant products are considered to be derived from the transition states with conformations having the larger substituent anti to the alkoxy group of the ester.

Asymmetric reactions of 8-phenylmenthyl pyruvate with allyltrimethylsilane, silyl enol ethers and ketene silyl acetals

By mediation of TiCl4, allylsilane, silyl enol ethers and ketene silyl acetals attacked (–)phenylmenthyl pyruvate and (–)-phenylmenthyl phenylglyoxylate at their si-faces. The reactions are hypothesised to proceed with rigid cyclic transition states: anti aldol adducts 16a and 17a were favourably obtained from E-ketene silyl acetals 6 and 7 having E-configuration, whereas syn aldol adducts 18b–21b were predominantly obtained from Z-ketene silyl acetal 18 and Z-silyl enol ethers 19–21.