Copper-catalyzed methylative difunctionalization of alkenes.

Trifluoromethylative difunctionalization and hydrofunctionalization of unactivated alkenes have been developed into powerful synthetic methodologies. On the other hand, methylative difunctionalization of olefins remains an unexplored research field. We report in this paper the Cu-catalyzed alkoxy methylation, azido methylation of alkenes using dicumyl peroxide (DCP), and di-tert-butyl peroxide (DTBP) as methyl sources.

Copper-Catalyzed Three-Component Carboazidation of Alkenes with Acetonitrile and Sodium Azide.

A copper-catalyzed three-component reaction of alkenes, acetonitrile, and sodium azide afforded γ-azido alkyl nitriles by formation of one C(sp )-C(sp ) bond and one C(sp )-N bond. The transformation allows concomitant introduction of two highly versatile groups (CN and N ) across the double bond. A sequence involving the copper-mediated generation of a cyanomethyl radical and its subsequent addition to an alkene, and a C(sp )-N bond formation accounted for the reaction outcome.

Copper-catalysed cyanoalkylative cycloetherification of alkenes to 1,3-dihydroisobenzofurans: development and application to the synthesis of citalopram.

A copper-catalysed cyanoalkylative cycloetherification of alkenes was developed. Heating a solution of substituted (2-vinylphenyl)methanol in MeCN/MeOH (v/v 7/3) in the presence of a catalytic amount of copper(ii) tetrafluoroborate hydrate [Cu(BF4)2·6H2O], bathophenanthroline, K3PO4, BnOH and (tBuO)2 afforded 1,3-dihydroisobenzofurans (phthalanes) via formation of one C(sp(3))-C(sp(3)) and one C(sp(3))-O bonds. A concise synthesis of citalopram, a marketed anti-depressant drug, was accomplished by applying this novel synthetic transformation.

Copper-Catalyzed Formal [2+2+1] Heteroannulation of Alkenes, Alkylnitriles, and Water: Method Development and Application to a Total Synthesis of (±)-Sacidumlignan D.

A copper-catalyzed three-component reaction of alkenes, alkylnitriles, and water affords γ-butyrolactones in good yields. The domino process involves an unprecedented hydroxy-cyanoalkylation of alkenes and subsequent lactonization with the creation of three chemical bonds and a quaternary carbon center. The synthetic potential of this novel [2+2+1] heteroannulation reaction was illustrated by a concise total synthesis of (±)-sacidumlignan D.

Sulfonamide and Tertiary Amine as Nucleophiles in Pd(II)-Catalyzed Diamination of Alkynes: Synthesis of Tetracyclic Indolobenzothiazine S,S-Dioxides.

Pd(II)-catalyzed oxidative double cyclization of the 1,2-diarylethynes bearing an N-methyl-N-(2-methoxycarbonyl)ethylamino and an aminosulfonyl group afforded indolobenzothiazine S,S-dioxides in good to excellent yields. The 2-(methoxycarbonyl)ethyl group attached to the indolyl nitrogen is readily removed under basic conditions (DBU, DMF, 120 °C) to provide the corresponding tetracycles with a free indolyl nitrogen in excellent yields.

2-(methoxycarbonyl)ethyl as a removable N-protecting group: synthesis of indoloisoquinolinones by Pd(II)-catalyzed intramolecular diamination of alkynes.

Pd(II)-catalyzed double cyclization of 1,2-diarylethynes bearing an N-methyl-N-[2-(methoxycarbonyl)ethyl]amino and an aminocarbonyl group at the ortho positions of the two aromatic rings afforded the tetracyclic N-[2-(methoxycarbonyl)ethyl]indoloisoquinolinones in good to excellent yields. The N-[2-(methoxycarbonyl)ethyl] group is readily removed under basic conditions (DBU, DMF, 120 °C) to afford the corresponding tetracycles with a free indolyl nitrogen in excellent yields. The 2-(methoxycarbonyl)ethyl as a removable N-protecting group is illustrated in other Pd(II)- and Pd(0)-catalyzed and selenium-mediated transformations.