Preparation of E -α-stannyl-β-trimethylsilylethynylacrylate, building block for polyconjugated ylidenebutenolide and its derivatives, by novel E -selective ethynylstannylation of propiolate

Trialkylborane-Mediated Multicomponent Reaction for the Diastereoselective Synthesis of Anti-δ,δ-Disubstituted Homoallylic Alcohols

The trialkylborane/O₂-mediated reaction of propargyl acetates having a tributylstannyl group at an alkyne terminus with aldehydes in a THF-H₂O solvent system gave anti-δ,δ-disubstituted homoallylic alcohols with good to high diastereoselectivity. Intriguingly, two alkyl groups derived from trialkylborane were embedded into the reaction product. The trialkylborane plays a key role not only as a radical initiator but also as a source of alkyl radicals.

Comparing Protonolysis and Transmetalation Reactions: Microcalorimetric Studies of C-AuI Bonds in [AuRL] Complexes

The protonolysis of C-Au bonds in [AuRL] organometallic complexes has been studied by calorimetry for 12 R groups. The experimental data have been combined with density functional theory calculations to obtain bond dissociation energy (BDE) values. The C-Au BDE values show a good correlation with the corresponding isolobal C-H BDE values. The heat released in the protonolysis of [AuRL] has also been measured for R = Ph and L = P(OPh)₃, PPh₃, PMe₃, PCy₃, and IPr, and these values strongly depend on the trans influence of L because of the mutual destabilization of the L-Au and Au-C bonds. The enthalpies of the transmetalation reaction [AuR(PPh₃)] + SnIBu₃ → [AuI(PPh₃)] + SnRBu₃ for seven R groups have been measured and compared with those of the corresponding [AuR(PPh₃)] protonolysis.

Stereocontrolled Synthesis of 19'-Deoxyperidinin

The stereocontrolled convergent synthesis of 19'-deoxyperidinin, 2, which might be a useful peridinin analog to understand the ICT characteristics, was efficiently achieved by sequential Pd-catalyzed cross-coupling reactions using bidirectionally extensible conjugated C5 olefin segments. The crucial 5(2H)-ylidenedihydrofuran function of 2 was successfully constructed by the Au-catalyzed regio- and stereoselective 5-exo-dig etherification.