A palladium-catalyzed enantioselective alkylative desymmetrization of meso-succinic anhydrides

Monoalkylation of cyclic anhydrides provides an opportunity to couple a carbon-carbon bond-forming event with the control of backbone stereochemistry. We have developed a palladium-JOSIPHOS catalyst system that desymmetrizes meso-succinic anhydrides using organozinc reagents as nucleophiles, and have found that, in many cases, this reaction proceeds at ambient temperature.     

A mild and facile synthesis of carboxylic anhydrides

Reaction of carboxylic acids with trimethylsilylethoxyacetylene in an inert solvent under mild conditions affords the corresponding carboxylic anhydrides in almost quantitative yields.     

A mild and efficient amidation of cyclic ethers catalyzed by rhodium caprylate

A small quantity of Rh₂(O₂CC₇H₁₅)₄ (2.5 mol % to 0.6 mol %) catalyzed the α-amidation of cyclic ethers under mild conditions, 35 °C, in the presence of electron-withdrawing p-chlorobenzenesulfonamide/PhI(OAc)₂ as the nitrene source, in CH₂Cl₂ for 4 h. The corresponding N-substituted amino cyclic ethers were successfully obtained in good yields (up to 87% based on 99% conversion) and compatibility with other oxidant sensitive structures in one-pot reaction.     

A catalytic asymmetric reaction involving enolizable anhydrides

In the presence of a highly efficient novel bifunctional organocatalyst at low loadings under mild conditions, enolizable homophthalic anhydrides can be added to a range of aromatic and aliphatic aldehydes to give dihydroisocoumarins, with excellent yields and diastereo- and enantiocontrol (up to 99% ee).     

A synthesis of succinimides and glutarimides from cyclic anhydrides

The transformation of cyclic anhydrides to their corresponding imides involves a mild three-step sequence: (1) reaction with a primary amine, (2) conversion of the intermediate monoamide to an N-hydroxysuccinimidyl ester using N,N′-disuccinimidyl oxalate (DSO), and (3) cyclization by heating the NHS ester in trichloroethylene in the presence of 4-(dimethylamino)pyridine.     

A highly efficient Pd-C catalytic hydrogenation of pyridine nucleus under mild conditions

A synergistic Pd-C catalytic hydrogenation of 4-pyridinecarboxamides straightforward to 4-piperidinecarboxamide hydrochlorides was developed in the presence of ClCH₂CHCl₂. It provided a novel strategy for highly efficient hydrogenation of pyridine nuclear by using low-cost Pd-C catalyst under mild conditions.     

Sustainable,mild and efficient p-methoxybenzyl ether deprotections utilizing catalytic DDQ

A procedure for the selective deprotection of p-methoxybenzyl ethers using catalytic amounts of DDQ and of sodium nitrite, with oxygen as the terminal oxidant, is reported.     

Reaction of anthranilic acid amides with cyclic anhydrides

Anthranilic acid amide reacts with cyclic anhydrides to give the corresponding N-acyl derivatives at the amino group, while analogous reactions of o-aminobenzohydroxamic acid lead lead to formation of 3-hydroxy-quinazolin-4-ones under mild conditions. N-Acyl derivatives of anthranilic acid amide undergo intramolecular cyclization to imides on microwave irradiation or on melting, and their treatment with acetic anhydride in the presence of sodium acetate on heating yields quinazolin-4-ones.     

Epoxides as alkene protecting groups. A mild and efficient deoxygenation

Dimethyl diazomalonate smoothly deoxygenates epoxides to alkenes with rhodium(II) acetate catalysis.     

A mild and efficient one-step synthesis of quinolines

2-Aminoaryl ketones undergo condensation with α-methylene ketones in the presence of a catalytic amount of Y(OTf)₃ at room temperature under mild conditions to afford the corresponding polysubstituted quinolines in excellent yields.     

A mild and efficient one-step synthesis of quinolines

[reaction: see text] The Friedl?nder synthesis of quinolines is an extensively employed protocol, yielding the desired heterocycle in a two-step reduction-condensation sequence. We have developed a mild, efficient, high-yielding single-step variant of this methodology, which employs SnCl(2) and ZnCl(2) to effect the reaction.     

Sulfur-containing heterocycles 14. New synthesis of cyclic anhydrides of 3-sulfinocarboxylic acids

3-Chlorosulfinylalkanoyl chlorides undergo cyclization into the corresponding five-membered mixed anhydrides (1,2-oxathiolan-5-one 2-oxides) under the action of sodium or mercury acetates. 2-Chlorosulfinylbenzoyl chloride gives 3H-2,1-benzoxathiol-3-one 1-oxide in high yield.     

A mild and efficient protocol for the conversion of carboxylic acids to olefins by a catalytic decarbonylative elimination reaction

A new method for the conversion of aliphatic carboxylic acids to olefins under unprecedented mild conditions is disclosed, wherein the carboxylic acids are converted in situ with pivalic anhydride to the mixed anhydrides, which regioselectively add to a PdCl(2)-DPE-Phos catalyst. At a temperature of only 110 degrees C, smooth decarbonylation and beta-hydride elimination occur, and the corresponding olefins along with CO, CO(2) and pivalic acid are liberated.     

A mild and efficient synthesis of thiolesters from alcohols

Numerous functionally diverse thiolesters are prepared in high yield in a mild “one-pot” synthesis from activated alcohols and thiolacids under Lewis acid catalysis.     

An efficient synthesis of optically active physostigmine from tryptophan via alkylative cyclization

[reaction: see text] A new and efficient synthetic route to physostigmine is described. Corey-Kim reagent reacted with tryptamine or tryptophan carbamates to give 3a-(methylthiomethyl)hexahydropyrrolo[2,3-b]indole skeletons. Formal total synthesis of racemic and chiral physostigmine was accomplished in excellent overall yields, in short steps.     

Reactions of cyclic anhydrides XI. A facile approach to pyrrolo-3, 1-benzoxazinones via anilic acids.

:ortho-Carboxymaleanilic acids (I) undergo intramolecular double cyclisation to give pyrrolo-benzoxazinones (II) in excellent yields when treated with sodium acetate-acetic anhydride whereas the corresponding fumaranilic acids (III) under these conditions furnish 3, 1-benzoxazinones (IV.)