16537-17-0

A practical direct preparation of tert-butyl esters from 2-tert-butoxypyridine has been developed. This system features the use of boron trifluoride·diethyl etherate in toluene solvent to rapidly achieve the reaction at room temperature. Using this reaction protocol, a variety of tert-butyl esters were synthesized from several different carboxylic acids at high yields. This practical procedure provides a promising and effective approach to the protection of carboxylic acids with a tert-butyl group.

We report a new method of metal-free alkoxycarbonylation. This reaction involves the generation of aryl radicals from arenediazonium salts by a very weak base (HCO2Na) under mild conditions. Subsequent radical trapping with carbon monoxide and alcohols gives alkyl benzoates. The conditions (metal-free, 1 equiv. base, MeCN, r.t., 3 h) tolerate various functional groups (I, Br, Cl, CF3, SF5, NO2, ester). Mechanistic studies indicate the operation of a radical aromatic substitution mechanism.

Tertiary butyl esters find large applications in synthetic organic chemistry. A straightforward method for the direct introduction of the tert-butoxycarbonyl group into a variety of organic compounds has been developed using flow microreactor systems. The resultant flow process was more efficient, versatile and sustainable compared to the batch.

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Transitions: The title reaction has been developed for the synthesis of a variety of tert-butyl benzoates by employing 1,10-phenanthroline as an additive. Various functional groups were tolerated and heteroaryl iodides were also suitable substrates. Preli

t-Butyl benzoates can be accessed from aromatic compounds bearing multiple halogen substituents via selective metal-halogen exchange with lithium tri-n-butylmagnesium ate complex followed by trapping with di-t-butyl dicarbonate.

A practical and green chemical process for the esterification of carboxylic acids with alcohols and transesterification of carboxylic esters in good to excellent yields by using K5CoW12O14· 3H2O (0.1 mol%) as catalyst is reported. The catalyst exhibited remarkable reusable activity. Georg Thieme Verlag Stuttgart.

Silica chloride has been found to be an efficient catalyst for esterification of carboxylic acids (aliphatic, aromatic and conjugated) with alcohols (primary, secondary and tertiary) as well as for transesterification of esters (by both alcoholysis and acidolysis).

The chemistry of di-tert-butyl disulfide polyoxide derivatives has been investigated.Low-temperature experiments permit the clear detection of vic-disulfoxides (α-disulfoxides).In addition, a proposal for a decomposition mechanism that accounts for the detection of one of the diastereoisomers and the formation of the final products has been advanced.The formation of di-tert-butyl thiosufonate was also shown to be solvent and concentration dependent.Finally, low-temperature experiments permit the detection of the sulfinyl sulfone and vic-disulfone derivatives.A general mechanism has been proposed for the decomposition of these disulfide polyoxide derivatives.

Oxidation of 1 equiv of S-(2-methyl-2-propyl) 2-methyl-2-propanesulfinothioate (1) with 2 equiv of m-chloroperoxybenzoic acid (MCPBA) gives S-(2-methyl-2-propyl) 2-methyl-2-propanesulfonothioate (4, 13percent), 2-methyl-2-propanesulfenic 2-methyl-2-propanesolfonic thioanhydride (5, 32percent), 2-methyl-2-propyl-3-chlorobenzoate (11, 4percent), 2-methyl-2-propyl 2-methyl-2-propanesulfinate (12, 22percent), and small amounts of bis(2-methyl-2-propyl) trisulfide (7) and bis(2-methyl-2-propyl) tetrasulfide (10).Possible mechanisms for product formation are discussed.

The peracid oxidation of seven alkyl iodides has been examined in nonpolar solvents.The stoichiometry for the reaction is shown to be (8 + n)ArCO3H + 6RI + 3H2O -> (8 + n)ArCO2H + 6ROH + 2I2 + I2O5 + (n/2)O2 (R = n-heptyl, Ar = m-ClC6H4, n = 4-16).Evidence is presented for the intermediacy of an alkyliodosyl compound in these oxidations.Primary alkyl iodides give exclusively displacement products, whereas secondary iodides give a mixture of products resulting from displacement, elimination, and α-carbon oxidation.Tertiary iodides give products resulting form displacement and elimination.Mechanisms for the formation of these products are presented.The overall rate of peracid mediated reaction is dependent upon the alkyl group: tertiary > secondary > methyl primary iodides.The bioactivation of organohalides via an analogous halogen oxidation process is discussed.