Rhodium-Catalyzed Parallel Kinetic Resolution of Racemic Internal Allenes Towards Enantiopure Allylic 1,3-Diketones
A rare case of a parallel kinetic resolution of racemic 1,3-disubstituted allenes by means of a rhodium-catalyzed addition to 1,3-diketones furnishing enantiopure allylic 1,3-diketones is described. Mechanistic experiments demonstrate that the different allene enantiomers react in parallel to either the diastereomeric E- or Z-allylic 1,3-diketones with the same absolute configuration of the newly formed stereogenic center. A broad substrate scope demonstrates the synthetic utility of this new method.
Hilpert, Lukas J.,Breit, Bernhard
p. 9939 - 9943
(2019/06/24)
Palladium- and Rhodium-Catalyzed Dynamic Kinetic Resolution of Racemic Internal Allenes Towards Chiral Pyrazoles
A complementing Pd- and Rh-catalyzed dynamic kinetic resolution (DKR) of racemic allenes leading to N-allylated pyrazoles is described. Such compounds are of enormous interest in medicinal chemistry as certified drugs and potential drug candidates. The new methods feature high chemo-, regio- and enantioselectivities aside from displaying a broad substrate scope and functional group compatibility. A mechanistic rational accounting for allene racemization and trans-alkene selectivity is discussed.
Hilpert, Lukas J.,Sieger, Simon V.,Haydl, Alexander M.,Breit, Bernhard
supporting information
p. 3378 - 3381
(2019/02/06)
Selective synthesis of allenes and alkynes through ligand-controlled, palladium-catalyzed decarboxylative hydrogenolysis of propargylic formates
Ligand-controlled regioselective palladium-catalyzed decarboxylative hydrogenolysis of propargylic formates is described. A wide range of allenes and alkynes were obtained by using either 1,2-diphenylphosphinoethane (DPPE) or 1,6-bisdiphenylphosphinohexane (DPPH) as a catalyst ligand.
The synthesis of allenes by Cu(i)-catalyzed regio- and stereoselective reduction of propargylic carbonates with hydrosilanes
Cu(i)-catalyzed anti-SN2′-type reduction of internal propargylic carbonates with hydrosilanes affords various di- and trisubstituted allenes with high regioselectivities; the reactions are compatible with functional groups and work efficiently