Acid-catalyzed cyclizations of E,E-dibenzylidenesuccinate esters have been developed as an efficient synthetic route to 1-aryl-1,2-dihydronaphthalenes. This reaction has been used in the synthesis of the naturally occurring lignans (+/-)-cagayanin and (+/-)-galbulin.

Gas-phase activation energies have been estimated for the dissociation of one and two phosphines from the cationic ruthenium complex [(η5-indenyl)Ru(HPPh2)3]+ (1) by the combined techniques of ES introduction and Fourier transform ion cyclotron resonance (FTICR) mass spectrometry (MS). These values are 16.6 ± 2.3 and 34.6 ± 2.3 kcal mol-1, respectively.

A short, efficient synthesis of the lignan (+)-lyoniresinol dimethyl ether is described. The synthesis is achieved by asymmetric photocyclization of an achiral dibenzylidenesuccinate to a chiral aryldihydronaphthalene. (-)-Ephedrine is used as a chiral auxiliary to bias the atropisomeric equilibrium in the dibenzylidenesuccinate prior to the photochemical reaction. The synthesis of the title compound was accomplished in five steps, and the final product was recrystallized to constant melting point and rotation.

2002 carboxylic acid derivatives carboxylic acid derivatives (naphthalene compounds) Q 0950 25 -090 Acid-Catalyzed Cyclization of 2,3-Dibenzylidenesuccinates: Synthesis of Lignans (±)-Cagayanin and (±)-Galbulin. --(DATTA, PROBAL K.; YAU, CHI; HOOPER, TIMOTHY S.; YVON, BRIGITTE L.; CHARLTON, JAMES L.; J. Org. Chem. 66 (2001) 25, 8606-8611; Dep. Chem., Univ. Manitoba, Winnipeg, Manitoba R3T 2N2, Can.; EN)