Highly Enantio- and Diastereoselective Brassard Type Hetero-Diels−Alder Approach to 5-Methyl-Containing α,β-Unsaturated δ-Lactones

Two efficient new chiral copper (II) Schiff base complexes were developed for the highly enantio- and diastereoselective HDA reaction of Brassard type diene 1b with aldehydes, to afford the corresponding 5-methyl-containing α,β-unsaturated δ-lactone derivatives in moderate yields, high enantioselectivities (up to 99% ee) and excellent diastereoselectivities (up to 99:1 anti/syn). On the basis of the absolute configuration of 4a−4j disclosed by X-ray diffraction and CD analysis, a possible transition-state model for the enantio- and diastereoselective catalytic reaction has been proposed

Indium(III)-Catalyzed Asymmetric Hetero-Diels–Alder Reaction of Brassard-Type Diene with Aliphatic Aldehydes

A highly diastereo- and enantioselective hetero-Diels–Alder (HDA) reaction of a Brassard-type diene with aliphatic aldehydes has been developed. The chiral N,N′-dioxide L2/In(OTf)3 complex was efficient toward the obtention of the corresponding β-methoxy-γ-methyl α,β-unsaturated δ-lactones in good yields (up to 86%) as well as dr and ee values (up to 97:3 cis/trans and 94% ee). In addition, the product 4a could be easily transformed into the methyl-protected epi-prelactone B by hydrogenation

Highly Enantio- and Diastereoselective Brassard Type Hetero-Diels−Alder Approach to 5-Methyl-Containing α,β-Unsaturated δ-Lactones

Two efficient new chiral copper (II) Schiff base complexes were developed for the highly enantio- and diastereoselective HDA reaction of Brassard type diene 1b with aldehydes, to afford the corresponding 5-methyl-containing α,β-unsaturated δ-lactone derivatives in moderate yields, high enantioselectivities (up to 99% ee) and excellent diastereoselectivities (up to 99:1 anti/syn). On the basis of the absolute configuration of 4a−4j disclosed by X-ray diffraction and CD analysis, a possible transition-state model for the enantio- and diastereoselective catalytic reaction has been proposed

Indium(III)-Catalyzed Asymmetric Hetero-Diels–Alder Reaction of Brassard-Type Diene with Aliphatic Aldehydes

A highly diastereo- and enantioselective hetero-Diels–Alder (HDA) reaction of a Brassard-type diene with aliphatic aldehydes has been developed. The chiral N,N′-dioxide L2/In(OTf)3 complex was efficient toward the obtention of the corresponding β-methoxy-γ-methyl α,β-unsaturated δ-lactones in good yields (up to 86%) as well as dr and ee values (up to 97:3 cis/trans and 94% ee). In addition, the product 4a could be easily transformed into the methyl-protected epi-prelactone B by hydrogenation

The expression levels and correlation of miR-5195-3p and GMFB.

(A) In HG-induced ARPE-19 cells, miR-5195-3p was significantly downregulated compared with that of NG group. (B) GMFB protein expression was upregulated in HG-induced ARPE-19 cells compared with that of NG group. ***p p < 0.01 compared with miR-NC. NC, negative control; HG, high glucose; NG, normal glucose; WT, wild type; MUT, mutant type.</p

Chiral <i>N</i>,<i>N</i>′‑Dioxide Organocatalyzed Asymmetric Electrophilic α‑Cyanation of β‑Keto Esters and β‑Keto Amides

An enantioselective electrophilic α-cyanation of 1-indanone-derived β-keto esters and β-keto amides using a hypervalent iodine as the cyanide-transfer reagent was realized. A chiral <i>N</i>,<i>N</i>′-dioxide was used as the efficient bifunctional organocatalyst in the presence of inorganic base, which gave the corresponding α-cyano dicarbonyl compounds in yields of 50–99% with good enantioselectivities (87–97% ee)

Highly Enantioselective Synthesis of Tetrahydroquinolines via Cobalt(II)-Catalyzed Tandem 1,5-Hydride Transfer/Cyclization

A chiral catalyst prepared from N,N′-dioxide and Co(BF4)2·6H2O was applied in the asymmetric hydride transfer initiated cyclization reaction, giving optically active tetrahydroquinolines in good yields with high enantioselectivities under mild reaction conditions. Meanwhile, in light of the absolute configuration of the product, a possible working model was proposed to explain the origin of the activation and asymmetric induction

Asymmetric Synthesis of 3,4-Diaminochroman-2-ones Promoted by Guanidine and Bisguanidium Salt

A highly enantioselective synthesis of 3,4-diaminochroman-2-ones has been realized via the domino reaction of o-hydroxy aromatic aldimines and azlactones. Notably, a cis-product was obtained as the major product by the use of guanidine 2a whereas a trans-product was the major product with bisguanidium salt 3•HBArF4. In two cases, various substituted 3,4-dihydrocoumarins were obtained with high yields (up to 99%) as well as excellent enantioselectivities (up to 99% ee) and diastereoselectivities (up to >99:1 cis:trans and 98:2 trans:cis, respectively) under mild reaction conditions

Asymmetric Organocatalytic Cyclopropanation of Cinnamone Derivatives with Stabilized Sulfonium Ylides

A simple chiral diamine catalyst 1h was successfully applied in the asymmetric cyclopropanation of cinnamone derivatives with stabilized sulfur ylides. The desired cyclopropanation adducts were obtained in moderate yields (up to 68%) with good enantioselectivities (67–93% ee) and excellent diastereoselectivities (>95:5) under mild conditions