Enantioselective Addition of Phenylacetylene to Ketones Catalyzed by Chiral Amino Alcohols

（S）-（1-Benzylpyrrolidin-2-yl）diphenylmethanol and cinchonine were evaluated as promotors in the asymmetric additions of phenylacetylene to ketones, in order to prepare chiral propargylic alcohols. Good yields （up to 89%） and moderate enantioselectivities （up to 77.9% ee） were achieved. Addition of Ti（OPr-i）4 can significantly improve the enantioselectivity of the reaction.

Synthesis,Characterization and Structure of Chiral Amino Acids and Their Corresponding Amino Alcohols with Camphoric Backbone

Chiral amino acids and their corresponding amino alcohols bearing camphoric backbone were prepared from D-（＋）-camphoric imide and characterized by infrared, elemental analysis, ESI-MS, and NMR measurements. Among them, one intermediate （1S,3R）-3-amino-2,2,3- trimethyl cyclopentane-1-carboxylic acid hydrochloride 3 was structurally elucidated by X-ray diffraction techniques. Versatile intermolecular hydrogen bonding interactions observed in its packing structure result in a two-dimensional framework.

New strategies for asymmetric photocatalysis: asymmetric organocatalytic/photoredox relay catalysis for efficient synthesis of polycyclic compounds containing vicinal amino alcohols

An asymmetric catalytic strategy in photocatalysis utilizing a chirality-induced approach through an organocatalytic/photoredox relay catalysis strategy is successfully achieved for the rapid construction of polycyclic compounds containing vicinal amino alcohols in a one-pot protocol. This methodology facilitates the efficient synthesis of diverse substituted polycyclic tetrahydroquinoline and benzofuran-derived vicinal amino alcohols, each containing five consecutive chiral centers, with high yields,excellent diastereoselectivities and enantioselectivities(up to 95% yield, >20:1 dr and 98% ee), under mild reaction conditions driven by sequential bifunctional squaramide organocatalyst-catalyzed [4+2] annulation and photocatalyst-catalyzed ketyl radical addition cyclization reaction process. Furthermore, investigations into the stereoselectivity mechanism and high-resolution mass spectrometry(HRMS) experiments on free radical trapping have provided evidence for elucidating the detailed mechanism of chirality-induced processes and chiral intermediate conversions in this procedure.

Synthesis and Crystal Structure of (2S,2'S,4'R)-2-(1-Hydroxy-1-ethylpropyl)-1-[(1'-p-tosyl-4'-hydroxypyrrolidin-2'-yl)methyl]pyrrolidine

The title compound （2S,2＇S,4＇R）-2-（1-hydroxy-1-ethylpropyl）-1-[（1＇-p-tosyl-4＇- hydroxypyrolidin-2＇-yl）methyl]pyrrolidine synthesized by using （2S,4R）-4-hydroxy-L-proline and L-proline as the main materials was characterized through IR, ^1H NMR, ^13C NMR and HRMS spectra as well as single-crystal X-ray diffraction analysis. There is one equivalent ethanol involved in the crystal （C23H40N2O5S, Mr = 456.63）. The crystal belongs to the triclinic system, space group P1, a = 6.5628（13）, b = 8.4228（17）, c = 11.957（2）°A, α= 80.54（3）,β= 83.19（3）, γ= 89.89（3）°, V= 647.3（2） °A^3, Z = 1, D, = 1.171 g/cm^3, λ（MoKα） = 0.71073°A,β = 0.158 mm^-1, F（000） = 248, the final R = 0.0465 and wR = 0.1336 for 1769 observed reflections with I〉 2σ（I）. The adjacent molecules of compound 5 are linked through intermolecular hydrogen bonds formed by the secondary hydroxy group of one molecule with the tertiary hydroxy group of another one, and the molecular chains are further linked by ethanol through two kinds of hydrogen bonds with two molecules from different chains respectively to form a supramolecular structure.

Graft of Chiral Amino Alcohol onto Poly（menthyl vinyl ketone） and the Grafted Polymer＇s Inducement to the Asymmetric Addition of Phenylacetylene to Aromatic Ketone

A new kind of optically active polymer bearing chiral amino alcohol was prepared by means of graft. The resulting grafted polymer was obtained as follows. First, the carbonyl of optically active helical poly（menthyl vinyl ketone）（poly-MVK） was reduced to hydroxyl group with lithium aluminum hydride as a reductant to yield poly（1-menthyl-2-propen-1-ol）（poly-MPO）. Second, the hydroxyl group of poly-MPO reacted with epichlorohydrin to yield methyloxirane-loading poly-MPO[（poly-MPO）-MO]. Third, the（poly-MPO）-MO reacted with amine to pro- duce optically active polymer bearing chiral amino alcohol[（poly-MPO）-APO]. The （poly-MPO）-APO was applied to the asymmetric addition of phenylacetylene to aromatic ketone. Good enantioselectivities were achieved and the catalyst could be recovered and reused 5 times with unchanged enantioselectivity and slightly decreased activity.