A Simple Strategy for the Preparation of 6-Substituted 3H-Benzoxazol-2-ones and 3H-Benzothiazol-2-ones

The double metallation of 6-bromo-3H-benzothiazol-2-one and 6-bromo-3H-benzoxazol-2-one with methyl magnesium bromide and alkyllithium bases is described. Alkylation with a variety of electrophiles occurs at the 6-position of the heterocycles in good yields.      

Synthetic Approach to 4a-Methyltetrahydrofluorene-Type Diterpenoids via an Aromatic Oxidation of Phenol Derivatives

An intramolecular aromatic oxidation of a phenolic compound with a hypervalent iodine reagent afforded the coupling product, in which the coupling took place at the para-position of the methoxy goup of the starting material instead of the desired para-position of the isopropenyl group, unfortunately.      

CuI/PPh3/PEG–Water: An Efficient Catalytic System for Cross-Coupling Reaction of Aryl Iodides and Alkynes

An efficient protocol for the copper-catalyzed Sonogashira coupling of aryl iodides with terminal acetylenes in water–polyethylene glycol has been established. Both electron-rich and electron-deficient aryl iodides were arylalkynated under microwave heating or reflux in oil bath to afford good to excellent yields.      

Effective Synthesis of 1,5-Disubstituted 2,1-Benzisothiazol-3(1H)-ones

A convenient and effective synthesis of novel 1,5-disubstituted 2,1-benzisothiazol-3(1H)-one derivatives is described. The approach involves nitration of inexpensive isatoic anhydride followed by its conversion to 5-nitro-2,1-benzisothiazol-3(1H)-ones in excellent yield and alkylation at the 1-position. The 5-amino group was further derivatized.      

Borane-catalyzed cascade Friedel–Crafts alkylation/[1,5]-hydride transfer/Mannich cyclization to afford tetrahydroquinolines

An unprecedented redox-neutral annulation reaction of tertiary anilines with electron-deficient alkynes was developed that proceeds through a cascade Friedel–Crafts alkylation/[1,5]-hydride transfer/Mannich cyclization sequence. Under B(C₆F₅)₃ catalysis, a range of functionalized 1,2,3,4-tetrahydroquinolines were facilely constructed in moderate to good yields with exclusive 3,4-anti-stereochemistry. The commercial availability of the catalyst and the high atom and step economy of the procedure, together with metal-free and external oxidant-free conditions, make this an attractive method in organic synthesis.

We report a redox-neutral annulation reaction of tertiary amines with electron-deficient alkynes under metal-free and oxidant-free conditions.     

Regioselective Intramolecular Carbon-Hydrogen Insertion in Copper-Catalyzed Carbenoid Decompositions of cis-1-Methyl-3-Arylcyclohexane-1-Diazomethyl Ketones : Some Synthetic Applications

Recently, we have developed¹ a new route for the stereo-specific introduction of an angular carboxyl or functionalized methyl groups² in a rigid hydrophenanthrene moiety. The key step in this approach is a regioselective intramolecular α-keto carbenoid insertion across the benzylic C-H bond (at C-4a) in CuSO₄-catalyzed thermal decomposition of the diazoketones and to the corresponding tetracyclic ketones and in moderate to good yields. A modified procedure³ of carbenoid decomposition of these diazoketones, in the presence of Cu₂O under irradiation with tungsten filament lamp, improves the yields of the desired C-H insertion products. Thus, the ketones and have been prepared now in consistently higher yields (53-55%) from the pure diazoketones , m.p. 125-127°, and , m.p.     

An Improved Synthesis of 4-Cycloheptenone

A previous paper² described the chemistry of 1-aza-4-cyclo-octene 1 which we prepared from 4-cycloheptenone 2 according to the method of Bahurel et al.³ This procedure involves the condensation of cis-1,4-dichloro-2-butene with ethyl sodio-acetoacetate, yielding, a mixture of four isomers 3–6. The entire mixture is then heated with aqueous potassium hydroxide under reflux for four hours. Under these conditions 5 undergoes decarbethoxylation to yield 4-acetylcyclopentene 7, while 3 yields 2, presumatly by Cope rearrangement atid decarbethoxylation (2 is present in almost negligiblequantity but was reported³ to also yield 2).     

Disodium Hydrogen Phosphate as an Efficient and Cheap Catalyst for the Synthesis of 2-Aminochromenes

An efficient and convenient method for the synthesis of 2-aminochromene by the one-pot, three-component reaction of an aromatic aldehyde, malononitrile, and α- or β-naphthol in the presence of a catalytic amount of disodium hydrogen phosphate under solvent-free conditions is described.