Synthesis of seven-membered lactones by regioselective and stereoselective iodolactonization of electron-deficient olefins.

A regio- and stereoselective iodolactonization of internal electron-deficient olefinic acids has been reported, which provides a straightforward access to a series of multi-functionalized seven-membered lactones containing two consecutive chiral centers. The ester substituents on the olefins played a key role in achieving high regioselectivity. This result was proved through experiments and DFT calculations.

Remote and Selective C(sp2)-H Olefination for Sequential Regioselective Linkage of Phenanthrenes.

Biphenylcarboxylic acid with two competing C(sp2)-H sites was designed for site selective C(sp2)-H functionalization by developing carboxylic acids assisted remote and selective olefination via 7-membered palladacycle. Mechanism investigation and DFT calculations reveal a kinetics-determined process, which could be utilized to explore a variety of remote site selectivity. The practicability of this method was highlighted by the precise construction of phenathrene under sequential site selectivity.

Late-Stage Modification of Tertiary Phosphines via Ruthenium(II)-Catalyzed C-H Alkylation.

Ru(II)-catalyzed direct alkylation of tertiary phosphines via hydroarylation of activated olefins promoted by mono-N-protected amino acid (MPAA) was achieved. This protocol provides a straightforward access to a large library of Buchwald-type bulky alkylated monophosphines from commercially available biaryl phosphine. Moreover, two ruthenacycle intermediates of tertiary phosphines via C-H bond cleavage were isolated to illustrate the mechanism of P(III)-directed C-H activation.

Ruthenium-Catalyzed Gram-Scale Preferential C-H Arylation of Tertiary Phosphine.

A general protocol for site-preferential mono-C-H arylation of tertiary phosphine ligands catalyzed by a ruthenium(II) complex was devised. This protocol gives access to a series of modified Buchwald-biaryl monophosphines on a gram scale in moderate to excellent yields. A catalytic cycle is proposed derived from knowledge of the intermediates observed by ESI-MS. Importantly, these monoarylated products could be further transformed into dibenzophosphole derivatives.