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The optical properties and intrinsic stress of Ta2O5 thin films deposited by dual ion beam sputtering (DIBS) were studied as a function of the assist ion beam voltage (250–650 V). When the assist ion beam voltage was in the range of 350–450 V, the transmittance at the quarter-wave point reached its highest value (lowest absorption). The refractive index increased to 2.185 as the assist ion beam voltage increased from 250 to 350 V, but decreased as the assist ion beam voltage was further increased from 350 to 650 V.

Treatment of allenyl-aldehyde dimethyl acetals with iodotrimethylsilane, titanium tetrachloride, and indium trichloride afforded a mixture of separable cis- and trans-2-haloalkenyl substituted 2-haloalkenylcycloalkyl methyl ethers by intramolecular nucleophilic attack of allene moiety to the oxonium ion generated by the reaction of TMSI, TiCl4, or InCl3 to dimethyl acetal moiety.

Triarylstibines react with iodobenzene diacetate in dichloromethane to afford triarylantimony(V) diacetates. The cross-coupling and carbonylative cross-coupling of triarylantimony(V) diacetates and dichlorides with organostannanes was accomplished in the presence of PdCl 2 (5 mol%) in CH 3 CN at room temperature.

The palladium Pd(PPh3)4-catalyzed coupling reaction of allenyl N-tosylcarbamates with hypervalent iodonium salts afforded the cyclized trans-5-substituted oxazolidinones, 3-oxazin-2-ones, and higher membered carbamates under mild conditions.

The Stille coupling of (Z)-1,2-bis(trimethylstannyl)ethenes with hypervalent iodonium salts (1 equiv) proceeded stereospecifically in the presence of PdCl2 (5 mol %) in DMF at room temperature to afford partially substituted (Z)-vinylstannanes under mild conditions. Alternatively, the use of 2 equivalents of hypervalent iodonium salts afforded tri-substituted alkenes.

Four stereoisomers of muricatacin 1a-d were prepared by the reaction of corresponding aldehydes 4a-d, which in turn were prepared from D-glucose, with the anion of triethylphosphonoacetate followed by reduction and cyclization under acidic conditions. Cytotoxicities of four stereoisomers were tested against in vitro A-549 cell line as well as MCF-7 cell line. Stereochemistry at C4 and C5 position of muricatacin did not affect the cytotoxicities significantly.

Pd(0)-catalyzed arylation of the aryl-substituted α-allenic alcohols with hypervalent iodonium salts afforded substituted trans-epoxides. Alternatively, arylation of the alkyl-substituted α-allenic alcohols in the presence of K 2 CO 3 afforded syn-diol cyclic carbonates and trans-epoxides in the presence of Cs 2 CO 3 .

Arylation and alkenylation of 1-ethoxy-1-trimetylsilyloxycyclopropane with diphenyliodonium tetrafluoroborate and alkenyliodonium tetrafluoroborate were accomplished by slow addition of silyloxycyclopropane to iodonium salts in the presence of Pd(OAc)2 (2 mol %) and DME H 2 O (4:1) to afford β-substituted ester. Alternatively, carbonylative coupling of silyloxypropane was carried out by slow addition of silyloxypropanes to iodonium salts under CO(1 atm) at room temperature in aqueous medium. The palladium-catalyzed coupling of ketene trimethylsilyl acetals with iodonium salts is also described.

The palladium-catalyzed coupling of organostannanes with iodanes(Koser's and Zefirov's reagents) in the presence of palladium catalyst was accomplished at room temperature under aqueous conditions to afford phenyl- or 4-iodophenyl-substituted products depending on the iodanes used.

Palladium-catalyzed arylation of allylic cyclic carbonates with iodobenzene in the presence of Pd(OAc), as catalyst afforded the phenyl-substituted allylic alcohols via palladium oxygen β-elimination. However, palladium-catalyzed arylation, alkenylation, and alkynylation of allylic cyclic carbonates with iodonium tetrafluoroborates afforded the phenyl, alkenyl, and alkynyl-substituted allylic cyclic carbonates without reductive ring opening under aqueous and nouaqueous conditions.

The coupling reaction of iodobenzene with allylic diols in the presence of Pd(OAc) 2 and n Bu 3 P as catalysts using K 2 CO 3 as base afforded the phenyl-substituted allylic diols. However, under the same reaction conditions with Et 3 N as base, phenyl-substituted α-hydroxy ketone was obtained.

Porcine pancreas lipase(PPL)-catalyzed acetylation of (±)-2-hydroxymethyl-3,4-dihydro-2 H -pyran with vinyl acetate in organic solvent afforded ( S )-(+)-2-acetoxymethyl-3,4-dihydro-2 H -pyran. Alternatively, (±)-2-acetoxymethyl-3,4-dihydro-2 H -pyran was resolved via hydrolysis catalyzed by PPL in acetone-phosphate buffer system to afford ( S )-(+)-2-hydroxymethyl-3,4-dihydro-2 H -pyran with high enantiomeric purity.

The alkyl substituted allylic cyclic carbonates 1a-d undergo elimination by using a catalytic amount of Pd(0) complex to form dienols 2a-b . However, on treatment of the unsubstituted or phenyl substituted allylic cyclic carbonates 1e and 1f with palladium(0) catalyst, deprotonation-elimination of π-allylpalladium complex followed by condensation with the other π-allylpalladium complex provided the coupled products 3a and 3b , respectively.

Reaction of chiral allylic and dienylic cyclic carbonates with various nucleophiles in the presence of (PPh 3 ) 4 Pd as a catalyst afforded α-, γ-, or e-substituted products with high regio-, ( E )-stereo-, and diastereoselectivity depending on nucleophiles.

Reaction of the cyclic carbonates of acyclic vinyl diols with RCu(CN)Li· BF 3 , RCu(CN)MgBr·BF 3 , or RMgBr·CuI (cat) in THF at −78 °C proceeded in S N 2′ fashion and resulted in the formation of alkylated ( E )-allylic alcohols with remarkably high diastereoselectivity. This reaction represents an efficient 1, 3-chirality transfer method.

Reaction of cyclic sulfites or carbonates of γ,δ-dihydroxy ( E )-α,β-enoates with R 2 Cu(CN)Li 2 , BF 3 ; RCu(CN)Li, BF 3 (R = Me-, n -Bu-) afforded either diastereoselective S N 2′products or reductive elimination product depending on reaction conditions. Addition of R 2 Cu(CN)Li 2 , BF 3 (R = Me-, n -Bu-) to cyclic sulfite ( 1 ) or cyclic carbonate ( 3 ) (inverse addition) afforded highly regio-, ( E )-stereo- and diastereoselectively α-alkylation products ( 6 and 8 ). By using this methodology, (2 S , 5 S )- trans -2-methyl-5-hexanolide, the pheromone of the carpenter bee Xylocopa hirutissima was synthesized.

(2R,3S)-1,2-Epoxy alcohols 1, (2S,3S)-2,3-epoxy alcohols 2, and (2S,3S)-1,2-epoxy alcohols 3 were prepared from readily available (−)-2-deoxy-D-ribose. Using epoxy alcohol 3b as a chiral synthon, (+)-disparlure, the pheromone of the gypsy moth, Porthetria dispar(L.), was synthesized.

(S)-3-Formyloxyaldehydes, chiral synthons for natural product synthesis were synthesized via highly stereoselective hydrogenation of the unsaturated furanose ring system derived from D-glucose or D-xylose. Alternatively, (R)-3-formyloxyaldehydes were prepared via deoxygenation of 3-hydroxyfuranoses derived from D-glucose or D-xylose.

The copper- and manganese-catalyzed homocoupling of aryl-, alkenyl-, and alkynylstannanes to afford biaryls. 1,3-dienes, and 1,3-diynes were achieved in the presence of iodine at 100 °C in good yields.

The copper iodide-catalyzed cross-coupling of polymer bound aryl iodide with organostannanes in N-methyl-2-pyrrolidone (NMP) was accomplished smoothly in the presence of NaCl.

The MnCl2·4H2O-catalyzed cross-coupling and carbonylative cross-coupling of organo-stannanes with hypervalent iodonium salts afforded biaryls and biaryl ketones, respectively.

Reaction of cyclic carbonates or sulfites of acyclic alkynyl diols with organocopper reagents proceeded in S N 2′ fashion and afforded α-allenic alcohols of high enantiomeric purity. The stereochemistry of this transformation was shown to be highly anti -diastereoselective.

The cyclic carbonates of acyclic vinyl diols react with nucleophiles in the presence of a palladium complex as a catalyst under neutral conditions to afford alkylated ( E )-allylic alcohols with highly regio-, and diastereoselectivity. This reaction represents an efficient 1,3-chirality transfer method.

(-)-(5R,6S)-6-Acetoxy-5-hexadecanolide, (-)-1, the natural mosquito oviposition attractant pheromone was synthesized from readily available carbohydrate, (-)-2-deoxy-d-ribose, using radical carbon-carbon bond formation as the key step.