Axially Chiral Phosphine-Oxazoline Ligands In The Silver(Ⅰ)-Catalyzed Asymmetric Mannich Reaction And Tertiary Amine-or Phosphine-Catalyzed Reactions Of Activated Olefins

Asymmetric catalysis is an important aspect of asymmetric synthesis, and one that has seen tremendous activity over the past decades. This dissertation mainly focuses on:(1) axially chiral phosphine-oxazoline ligands in the silver(I)-catalyzed asymmetric Mannich reaction; (2) the discovery of some tertiary amine-or phosphine-catalyzed reactions of activated alkenes especially for their asymmetric versions. This dissertation contains three parts:Part I:Axially chiral phosphine-oxazoline ligands in the silver(I)-catalyzed asymmetric Mannich reaction. (1) Axially chiral phosphine-oxazoline ligand I-I-L7, prepared from (S)-binol, was found to be a fairly effective chiral ligand in silver(I)-catalyzed asymmetric Mannich reaction of fluorinated aldimines with trimethylsiloxyfuran to give the corresponding adducts in up to 99%yield, over 20:1 dr and 81%ee. (2) Based on the work of (1), a highly regio-and enantioselective asymmetric vinylogous Mannich reaction of readily available fluorinated aldimines bearing a chiral auxiliary [(S)-1-phenylethyl group] with siloxyfurans to afford chiral fluorine-containing y-butenolide derivatives in up to 99%yield along with over 20:1 dr and 99%ee has been developed in the presence of silver acetate (10 mol%) and axially chiral phosphine-oxazoline ligand I-I-L1 (11 mol%). (3) Axially chiral phosphine-oxazoline ligand I-I-L6 derived from (R)-binol was identified as a fairly effective chiral ligand in silver(I)-catalyzed asymmetric Mannich reaction of N-Boc aldimines with trimethylsiloxyfuran, giving the corresponding adducts in up to 97%yield,7:1 dr and 86%ee (major diastereoisomer). Since the N-protecting group (N-Boc) can be readily cleaved under several convenient acidic conditions(HCl or TFA), this reaction will be useful in organic synthesis.Part II:Chiral tertiary amine-or phosphine-catalyzed reactions of electron-deficient allenes with activated alkenes (C=C). (1) D-Threonine-L-tert-leucine-based bifunctional phosphine-catalyzed highly enantioselective [3+2] annulation of allenes with maleimides has been disclosed, affording the corresponding functionalized bicyclic cyclopentenes containing two tertiary stereogenic centers in good to high yields and with good to high enantioselectivities. The plausible reaction mechanism and the further transformation of cycloadducts have been also disclosed. (2) The first example ofβ-ICD catalyzed highly enantioselective intermolecular Rauhut-Currier reaction of maleimides with allenoates and penta-3,4-dien-2-one has been also disclosed, allowing the synthesis of optically active functionalized allene derivatives in good to high yields along with good to excellent enantioselectivities. These chiral functionalized allenic derivatives can be further transformed to the corresponding chiral y-butenolide derivatives and furan derivatives in good yields in the presence of transition metal catalysts.Part III:Tertiary amine-catalyzed reactions of electron-deficient allenes with activated ketones (C=O). (1) We have developed the first asymmetric organocatalytic formal [2+2] cycloaddition of trifluoromethylketones and allenoates using (3-isocupreidine (β-ICD) as a catalyst to afford S-configured 2-alkyleneoxetanes in moderate to good yields along with good to high diastereoselectivities and enantioselectivities. (2) We have disclosed a 4-(N,N-dimethylamino)pyridine (DMAP)-catalyzed Morita-Baylis-Hillman reaction of isatins with allenoates, affording the corresponding adducts in good to high yields with moderate diastereoselectivities. This is the first example on the Morita-Baylis-Hillman reaction of the carbonyl group in activated ketone with electron-deficient allenic ester.