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Diastereoselective palladium-catalyzed formate reduction of allylic carbonates presents unique opportunities for application in organic synthesis provided that stereoselectivity in the course of this metal-catalyzed reaction can be controlled. Developments on efficient metal-catalyzed process exploiting resident stereocenters on the substrates as a means to control stereoselectivity en route to preparing propionate units containing an array of stereochemical patterns are presented.

Alkylation of metal carbonate in various ionic liquids with 1-bromo-3-phenylpropone as a model reactant was investigated. A new phosgene-free method for the synthesis of symmetrical organic carbonates through alkylation of metal carbonate with various alkyl halides and sulfonates in 1-n-butyl-3-methyl-imidazolium hexafluorophosphate, as an ecofriendly reaction media was reported.

A demonstration showing that the bis(triphenylphosphine)immium (PPN) manganese carbonyls and more interestingly the off-the-shelf reagent PPN(super +)Cl(super -) are good catalysts for the coupling reactions of CO2 with epoxides to yield cyclic carbonates is presented. The reactions are clean with no polycarbonate contamination and are performed in neat substrates with no need of organic solvents.

The reactions of anilines with 4-nitrophenyl, 4-methylphenyl, and 4-chlorophenyl 4-nitrophenyl carbonates are studied in the aqueous ethanol, to clarify the mechanisms of the aminolysis of diaryl carbonates. The main goal is to evaluate the influence of the amine nature and that of the leaving and nonleaving groups of the carbonate on the kinetics and mechanisms.

The reaction of CO2 with a variety of epoxides is examined in the presence of ionic liquids (ILs) wherein tetrahaloindate(III)-based ILs are found to exhibit interactions in the [Q][InX3Y]-catalyzed coupling reactions. The effects of various parameters such as temperature, pressure, and molar ratio of propylene oxide to catalyst are investigated, and the plausible reaction mechanism based on the (super 1)H and (super 13)C NMR studies is presented for the formation of propylene carbonate.

Benzotriazole reagents for thioacylation, thiocarbamoylation, aryl/alkoxy-thioacylation, and aryl/alkythiothiocylation are synthesized. Their utility is assessed of representative hetroaryl thioureas, thioamides, thionoesters, thiocarbamates, thuiocarbamates, thiocarbonates, and bithiocarbonates.

Phenyl 4,6-di-O-benzyl-2,3-O-carbonyl-beta-D-glucothiopyranoside and the regiosiomeric phenyl 2,6-di-O-benzyl-3,4-O-carbonyl-beta-D-glucothiopyranoside are prepared and studied as glucosyl donors at -60 degrees Celsius in dichloromethane with preactivation by 1-benzenesulfinyl piperidine before addition of the acceptor alcohol. The 2,3-O-carbonate protected donor showed moderate to excellent beta-selectivity under these conditions depending on the acceptor employed.

The reactions of secondary alicyclic (SA) amines with O-4-nitrophenyl S-methyl thiocarbonate, O-(2,4-dinitrophenyl) S-methyl thiocarbonate and with O-(2,3,4,5,6-pentafluorophenyl) S-methyl thiocarbonate are examined in order to study the kinetics and mechanisms of the aminolysis of O-aryl S-alkyl thiocarbonates. The reactions of quinuclidines (QUI) with O-4-nitrophenyl S-methyl thiocarbonate and with O-(2,4-dinitrophenyl) S-methyl thiocarbonate are hence examined.

Enantioenriched 4-hydroxyalk-2-ynyl carbonates are prepared by stereoselective zinc-mediated addition of alkyl 2-propynyl carbonates to aldehydes. Their partial reduction to Z-olefins followed by cyclization under mild Pd-catalyzed conditions allowed a straightforward access to enantioenriched syn-1,2-diols protected as cyclic carbonates.

The synthesis of 2-substituted indenes is achieved through a palladium-catalyzed carboannulation of propargylic carbonates with nucleophiles. This new method has accommodated a variety of nucleophiles and has afforded the substituted indenes in good yields.

One-pot synthesis of 2-aminobenzoxazoles by using commercially available tetramethyl orthocarbonate or 1,1-dichlorodiphenoxymethane, an amine, and an optionally substituted 2-aminophenol is described. The scope of the reactions conducted under mild conditions which provided 2-aminobenzoxazoles in modest to excellent yields was examined by using a variety of amines and substituted 2-aminophenols.

The combined use of the bimetallic aluminum(salen) complex [[Al(salen)].sub.2]O and tetrabutylammonium bromide (or tributylamine) has catalyzed the reaction between epoxides and carbon disulfide, which has produced 1,3-oxathiolane-2-thiones and 1,3-dithiolane-2-thiones as main products. The structure and stereochemistry of three of the 1,3-dithiolane-2-thiones is determined and is used to correct errors concerning the synthesis of cyclic di- and trithiocarbonates.

Palladium(0)-catalyzed cyclization of bromoallenes, propargyl chlorides, and carbonates bearing hydroxy and benzamide groups as internal nucleophiles has produced functionalized tetrahydrofuran. Cyclization reactivity is dependent on the relative configuration of the benzamide and leaving groups and the bis-cyclization is used as the key step in a short total synthesis of pachastrissamine.

Several experimental and theoretical analyses are conducted to explain the nucleofugality patterns that are observed in the aminolysis, as well as phenolysis of the various S-aryl and O-aryl thiocarbonates. A comparison of the relative structures in the two complexes is also presented.

Iodoalkyl tert-butyl carbonates and carbamates have undergone clean free-radical addition to thiomaleic anhydride to produce substituted thiosuccinic anhydrides on treatment with tris(trimethylsilyl)silane and a radical initiator. The tert-butyloxycarbonyl group is converted to amides through reaction with electron-deficient sulfonamides or to aldehydes and ketones by the reactions of thioesters with either thiophenol or phenylboronic acid.

The Bronsted plots for the concerted pyridinolysis of aryl 2,4,6-trinitrophenyl carbonates is described. The concerted mechanism is attributed to the title carbonates which possess two O-aryl groups and one exceptionally good nucleofuge.

The displacement of a methylsulfinyl group from the 6-position of the pyridine ring is used to explain the characteristics of 2-aminopyridines with a variety of polar 6-substituents. The synthesis of 6-thiomethyl pyridines from reaction of 2-(l-phenylethylidene)propanedinitriles with dimethyl N-cyanodithiominocarbonate is also described.

Enantiomerically pure 1-arylpropenols are prepared by resolution of the corresponding racemates by using the lipase formulation Novozyme 435. Deprotonation of the latter alcohols with n-BuLi, followed by derivatization with ([(t-BuO).sub.2]CO, has produced the corresponding carbonates.

Neighboring group participation in glycopyranosylation reactions is detected for esters at the 3-O-axial and -equatorial, 4-O-axial and -equatorial, and 6-O-sites of a range of donors through the use tert-butoxycarbonyl esters. The studies have not provided any evidence for the fragmentation of carbonate esters at the 3-O-equatorial, 4-O-axial and -equatorial and 6-O positions, indicating that neighboring group participation from those sites have not occurred under typical glycosylation conditions.

The palladium-catalyzed intermolecular substitution reaction of soft nucleophiles with allylic acetates and carbonates is analyzed. The stereochemistry of the cyclopentenone and the ratio of HWE to aldol products are dependent upon the choice of based used in the reaction.

The development of a one-pot method to prepare various 1-alkyl-2,2,2-trifluoro-1-trim-ethylsilyloxyethylphosphonate and 1-aryldifluoroethenyl phosphate compounds is reported. The reaction uses readily available acyl phosphonates and trifluoromethyltrimethylsilane under very mild conditions.

A study is conducted to determine the nucleofuge-specific parameters for phenyl carbonate and methyl carbonate leaving group in different solvents. Kinetic measurements showed that phenyl carbonates is more stable as it solvolyze one order of magnitude faster than methyl carbonates.

The ability of telluroxide compounds exhibit hydrolysis is reported for the first time. It is observed that 6,6'-telluroxy-bis(6-deoxy-beta-cyclodextrin) acts as a hydrolase mimic and displays a significant rate acceleration of 106 000 for the hydrolysis of 4,4'-dinitrodiphenyl carbonate.

The highly selective palladium-catalyzed allylation of a variety of 1,1-disubstituted allylic carbonates with substituted dialkylaminomalonate derivatives to form the Z-olefin product is reported. The results have shown that the Z-olefin product can be formed regardless of whether the E- or Z-allylic carbonate is used as starting material.

O-N intramolecular alkoxycarbonyl (carbonate-carbamate) migration occurs as a common reaction of hydroxyamino acids under mild basic aqueous conditions with no formation of side products. Carbonate protective groups migrate to produce amino-protected carbamate derivatives of hydroxyamino acids with high efficiency and purity.

The intermediates formed in the reaction of an alcohol with dicyclohexylcarbodiimide (DCC) in the presence or absence of carbon dioxide are isolated or identified. The reaction of adding alcohol to the cumulene is tested with various aliphatic alcohols such as methanol, ethanol, and allyl alcohol and the driving force of this reaction is the conversion of carbodiimide into the relevant urea, which is some 35kcal/mol downhill with respect to the parent compound.

A reaction mechanism is proposed that the oxazolidinone is obtained from an oxazinone intermediate via a bicyclo[2.2.1] intermediate. The five-membered ring compound, oxazolidinone, is more stable than the six-membered ring compound, oxazinanone.

Quantitative relationships are reported between the global electrophilicity index and the experimental rate coefficients for the reactions of thiolcaronates and dithiocarbonates with piperidine. The validated scale of electrophilicity is then used to rationalize the reaction mechanism of these systems.

The utility of propargyloxycarbonyl chloride in simultaneous protection of alcohols and amines is explored and the selective deblocking of propargyl carbonates in the presence of propargyl carbamates with benzyltriethylammonium tetrathiomolybdate under mild conditions is achieved. The observation offers a new protecting strategy where an amine and an alcohol group can be protected simultaneously in one pot, and in later synthetic step, is the alcohol group has to be deprotected selectively.

Research has been conducted on aliphatic alcohols. The authors describe palladium catalysis-mediated method developed to investigate aliphatic alcohols' coupling with allyl carbonates, and they report the presence of transient allyl carbonates in the couplings.

Research has been conducted on pyrido[2,3-b][1,4]oxazin-2-ones. The authors describe the preparation of these compounds via one-pot annulation of N-substituted-2-chloroacetamides with 2-halo-3-hydroxypyridines using cesium carbonate in refluxing acetonitrile.

Less is known on the mechanisms of the aminolysis of thiocarbonates and thioacetates, particularly thionocarbonates, although the mechanisms of the aminolysis of alkyl aryl and diaryl carbonates and aryl acetates are well understood. Under amine excess over the substrates pseudo-first-order rate coefficients are obtained for all the reactions.