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Structure units containing all-carbon quaternary stereogenic center are found in many bioactive natural products. However, enantioselective construction of this type of structure units has been a formidable challenge for synthetic community due to the steric hindrance enforced by all-carbon quatemary stereocenters. In this review, we present the achievements made by Chinese scientists in the area of asymmetric synthesis of all-carbon quaternary stereocenters in natural products during the past two years.

The first enantioselective total synthesis of（＋）-preussin B and an improved synthesis of the antifungal alkaloid（＋）-preussin are described. Our approach relied on the four step-economical synthetic methods developed in our laboratory：（1） the cis-diastereoselective reductive dehydroxylation of hemiaminals;（2） the direct amide/lactam reductive alkylation;（3） the one-pot N,O-bisdebenzylation-N-methylation; and（4） the one-step synthesis of malimide from malic acid. Both total syntheses are quite concise, which have been achieved in six steps, and gave overall yields of 25.7% and 27.6%, respectively.

Enantioselective functionalization of prochiral C-H bonds is a highly attractive strategy for the construction of chiral compounds.Despite extensive efforts[1],enantioselective C（sp3）-H functionalization still remains challenging at present.For instance,although enantioselective C-H functionalization via desymmetrization of two carbon centers has been accomplished with Pd catalysis and a directing group,differenciation of the prochiral C-H bonds on one methylene carbon center has rarely been achieved.On a different front,introduction of a transient chiral directing group is expected to be useful in enantioselective C-H arylation of C（sp2）-H bonds.Nevertheless,

Chiral separation that is closely related to daily life is a meaningful research. Polysaccharide-（e.g., cellulose, amylose derivatives） based chiral packing materials afford powerful chiral stationary phases（CSPs） toward a broad range of racemic compounds. However, considering the explosive growth of specific chiral drugs, the separation efficiencies of these CSPs need further improvement, which calls for new approaches and strategies. Smart polymers can change their physical or chemical properties dynamically and reversibly according to the external stimuli（e.g., thermo-, pH, solvent, ion, light, critical parameters for chromatographic separation） exerted on them, subsequently resulting in tunable changes in the macroscopic properties of materials. In addition to their excellent controllability, the introduction of chiral characteristics into the backbones or side-chains of smart polymers provides a promising route to realize reversibly conformational transition in response to the chiral analytes. This dramatic transition may significantly improve the performance of materials in chiral separation through modulating the enantioselective interactions between materials and analytes. With the help of chirality-responsive polymers, intelligent and switchable CSPs could be developed and applied in column-liquid chromatography. In these systems, the elution order or enantioselectivity of chiral drugs can be precisely modulated, which will help to solve many challenging problems that involve complicated enantiomers. In this paper we introduce some typical examples of smart polymers that serve as the basis for a discussion of emerging developments of CPSs, and then briefly outline the recent CSPs based on natural and certain synthetic polymers.

β-Di-substituted α-amino acids （AAs） contain adjacent carbon stereogenic centers and pose considerable synthetic challenge. Complementary to the conventional synthesis strategies based on the transformation of existing functional groups, we envi- sioned these molecules could be quickly accessed via selective functionalization of sp3 hybridized C-H bonds on the side chains of common α-AA precursors. We report a readily applicable method to prepare β-alkynyl α-amino acids via Pd-cata- lyzed diastereoselective C（sp3）-H alkynylation of common α-amino acids precursors with acetylene bromide.

A full account of the novel and flexible approach to hydroxylated 8-azabicyclo[3,2,1]octan-3-ones and 9-azabicyclo[3,3,1] nonan-3-ones is presented. Using keto-lactams as the starting materials, this two-step method consists of silyl enol ether for mation with TBDMSOTf, lactam activation with Tf20/DTBMP, and halide-promoted cyclization. Radical dechlorination of the resulting 1-halotropan-3-ones led to the corresponding hydroxylated tropan-3-ones, which can be hydrogenated to yield 3ct,613-dihydroxytropanes. Starting from optically active keto-lactams, the method has been applied to the enantioselective syntheses of （＋）-（1S,3S,5R,6S）-pervilleine C （6）, （＋）-（1S,3R,5S,6R）-valeroidine （3）, （＋）-（1S,3S,5R,6S）-dibenzoyloxytropane （8） and （＋）-（1S,3S,5R,6S）-merredissine （9）.

A series of novel supramolecular organocatalysts of hydroxyprolinamide based on the upper rim of calix[4]arene scaffold have been developed to catalyze enantioselective multi-component Biginelli reaction. Under the optimal conditions, the reactions occurred with moderate-to-excellent enantioselectivities （up to 98% ee）. A plausible transition state constructed by the supramolecular interaction of hydrogen bond and cation-π between catalysts and substrates has been proposed.

A novel and concise synthetic access to enantiopure chiral 2-aryl/alkyl substituted 4-piperidone has been demonstrated. This new route features two key steps： the highly diastereoselective conjugate addition of homochiral lithium amides to trans-β-substituted-α,β-unsaturated methyl esters guaranteed the enantiopurity at 2 position （de 〉19：1） and the intramolecular attacking of carbanions to methyl esters led to the formation of the piperidone ring. A wide range of substrates, including chiral 2-aryl and 2-alkyl-4-piperidones, were successfully synthesized with modest to high yield. Moreover, some non-chiral 3-substituted-4-piperidones were also synthesized with enhanced ring-formation yield, implicating the versatility of this meth- od in construction of various piperidine rings.

As one of the most important five-member heterocyclic aromatic rings, pyrrole is widely distributed in numerous natural products and pharmaceutical agents. Asymmetric dearomatization of pyrroles is very attractive in organic synthesis given the fact that highly functionalized chira pyrrolines and pyrrolidines could be easily accessed from the readily available pyrroles. However, the reported asymmetric dearomatization reactions of pyrroles are limited to transition-metal-catalyzed [4＋3] cycloaddition and hydrogenation reactions.

The BINOL-amino alcohol enantiomeric pair （S）-I and （R）-I are discovered to conduct both enantioselective and diastereose- lective fluorescent discrimination of the four stereoisomers of threonine derivatives. This study utilizes different fluorescence responses of one sensor at two emission wavelengths toward the stereoisomeric substrates which expands the capability of the sensor in chiral recognition. In addition, the sensor pair also allows visual recognition of the N-protected L-allo-threonine and D-allo-threonine by enantioselective precipitation.