Regio- and stereospecific rhodium-catalyzed allylic alkylation with an acyl anion equivalent: an approach to acyclic α-ternary ß,γ-unsaturated aryl ketones.

The regio- and stereospecific rhodium-catalyzed allylic alkylation of secondary allylic carbonates with cyanohydrin pronucleophiles facilitates the direct construction of acyclic α-ternary ß,γ-unsaturated aryl ketones. Interestingly, this study illustrates the impact of deaggregating agents on regiocontrol and the electronic nature of the aryl component to suppress olefin isomerization. In addition, we demonstrate that the dimethylamino substituent, which modulates the pKa of the α-ternary ß,γ-unsaturated aryl ketone, provides a useful synthetic handle for further functionalization via Kumada cross-coupling of the aryl trimethylammonium salt. Finally, the stereospecific alkylation of a chiral nonracemic secondary allylic carbonate affords the enantioenriched α-ternary aryl ketone, which was employed in a formal synthesis of trichostatic acid to illustrate that the allylic alkylation proceeds with net retention of configuration.

Rhodium-catalyzed allylic substitution with an acyl anion equivalent: stereospecific construction of acyclic quaternary carbon stereogenic centers.

A highly regio- and stereospecific rhodium-catalyzed allylic alkylation of tertiary allylic alcohol derivatives with a cyanohydrin pronucleophile is described. This direct and operationally simple protocol provides a fundamentally novel approach toward the synthesis of α-quaternary substituted ketones and circumvents many of the inherent problems associated with conventional enolate alkylation reactions. The stereospecific variant of this reaction provides the enantiomerically enriched α-quaternary substituted allylic aryl ketone, which is a particularly challenging intermediate for more conventional enolate-based strategies.

Regioselective one-step synthesis of 4-fluoroalkylated isoquinolines via carbopalladation reaction of fluorine-containing alkynes.

[reaction: see text] The palladium-catalyzed annulation reaction of fluoroalkylated alkynes with various 2-iodobenzylidenamines was investigated. In the presence of a catalytic amount of Pd(PPh3)4, the reaction took place smoothly to give the corresponding 4-fluoroalkylated isoquinoline in high yield as a single isomer. No other regioisomer was detected.

A facile regiocontrol in the palladium-catalyzed annulation of fluorine-containing internal alkynes with variously substituted 2-iodoanilines: a new regioselective synthesis of 2- or 3-fluoroalkylated indole derivatives.

Treatment of various types of fluoroalkylated alkynes with o-iodoaniline in the presence of Pd(PPh(3))(4) in DMF at 80 degrees C for 8 h mainly gave 2-fluoroalkylated indoles in high yields. The use of P(o-Tol)(3) instead of PPh(3) as a ligand led to the preferential formation of 3-fluoroalkylated indoles in high yields. Interestingly, the reaction of trifluoromethylated alkynes bearing a benzylic substituent afforded 2- or 3-trifluoroethylated indole derivatives in good yields.

Highly regio- and stereoselective carbostannylation reaction of fluorine-containing internal acetylenes with allylstannanes.

Carbostannylation of fluoroalkylated alkynes with various allylstannanes in the presence of AIBN was investigated. In the case of the allylstannane having an electron-withdrawing group at the beta position, the reaction proceeded highly regio- and stereoselectively to give the corresponding allylstannylated products in high yields. Even in the absence of AIBN, the reaction took place smoothly in a highly regio- and stereoselective manner under an atmosphere of air. Thus-obtained vinylstannanes were subjected to the Migita-Kosugi-Stille coupling reaction conditions, affording the tetrasubstituted alkenes in excellent yields.

A sequential highly stereoselective hydroboration and Suzuki-Miyaura cross-coupling reaction of fluoroalkylated internal acetylenes: a practical one-pot synthesis of fluoroalkylated trisubstituted alkenes.

The one-pot synthesis of trisubstituted alkenes starting from fluoroalkylated internal alkynes was investigated. Hydroboration of the alkynes proceeded in a highly regio- and stereoselective manner to give the corresponding vinylboranes in excellent yields. Without isolation, treatment of the vinylboranes with various aryl halides under the Suzuki-Miyaura cross-coupling conditions gave the fluoroalkylated trisubstituted alkenes in high yields with complete retention of the olefinic geometry.

A highly regio- and stereoselective carbocupration of fluoroalkylated internal alkynes: a short total synthesis of the antiestrogenic drug panomifene.

[reaction: see text] A highly regio- and stereoselective carbometalation reaction of fluoroalkylated internal alkynes with organocopper reagents is described. This reaction is utilized successfully in the short, stereoselective total synthesis of the antiestrogenic drug panomifene.