Catalytic enantioselective 1,3-dipolar cycloaddition between imino esters and electrophilic alkenes, employing chiral metal complexes derived from copper(I) and silver(I) salts and (S)-DM-or (S)-DTBM-Segphos as ligands produces diastereodivergently exo-or endo-cycloadducts, respectively. The effect of the functional group of the dipolarophile and the fine tuning of the catalyst plays an important role in promoting reverse diastereoselectivities. The origins of experimentally observed enantioselectivity and diastereoselectivity data, as well as the origin of the observed switched endo/exo ratios, are also explained by means of density functional theory calculations.

Asymmetric hydrogenation (AH) and asymmetric transfer hydrogenation (ATH) are versatile synthetic methodologies widely employed in the preparation of chiral compounds. In this review, we explore the applications of AH and...

3-Arylidenechroman-4-ones and 2-arylidene-1-tetralones are hydrogenated to cis-benzylic alcohols in dr’s and er’s up to 99:1 via a CC and CO one-pot reduction in the presence of 2–5 mol % Noyori–Ikariya-type RuII chiral complexes and HCO2Na as a hydrogen source under asymmetric transfer hydrogenation–dynamic kinetic resolution (ATH-DKR) conditions. The oxidation of theses substrates resulted in the enantioselective synthesis of the natural homoisoflavanone dihydrobonducellin and its carba-analogues.

Neste trabalho, 3-haloacetil-4-metilquinolinas foram sintetizadas a partir da reação de 4-alcóxi-3-alquen-2-onas [R In this work, 3-haloacetyl-4-methylquinolines were synthesized from the reaction of 4-alkoxy-3-alken-2-ones [R 1 C(O)CH=C(R 2 )OCH 3 , where R 1 = CF 3 , CCl 3 , CHCl 2 , CF 2 Cl, CF 2 CF 3 and R 2 = Me, Et, Pr, Bu, i-Bu and i-Pe] and 2-aminoacetophenone. The reaction was performed in ionic liquid and 4-toluene sulfonic acid under microwave irradiation. Results showed that the catalytic method was effective. Products were formed in a short time (10-20 min) and presented good yields (70-91%).

Noyori‐Ikariya RuII complexes promoted the one‐pot C=C/C=O bonds reduction of isoflavones using sodium formate as the hydrogen source through Asymmetric Transfer Hydrogenation‐Dynamic Kinetic Resolution (ATH‐DKR). Due to the neutral conditions employed, isoflavones with different substituents at the 2’‐position of B‐ring (H, OH, OMe and Br) were successfully reduced. Ten cis‐3‐phenylchroman‐4‐ols were selectively obtained (>20 : 1 dr) in good yields (up to 86 %) and excellent enantioselectivities (up to >99 : 1 er). The synthetic applications of these chiral compounds were also demonstrated. Enantioenriched isoflavanones were obtained under mild metal‐free oxidation of the cis‐3‐phenylchroman‐4‐ols while pterocarpans were synthesized by two strategies: an acid‐catalyzed cyclization and a novel approach based on a Pd‐catalyzed C−O intramolecular cross‐coupling reaction.

The oxo-tethered-Ru(II) precatalyst promoted the one-pot C�C/C�O reduction of chalcones using sodium formate as the hydrogen source in water through asymmetric transfer hydrogenation. Twenty-seven 1,3-diarylpropan-1-ols were obtained in good to excellent yields (up to 96%) and enantiomeric purities (up to 98:2). Our data suggested that the enones are first reduced to the corresponding dihydrochalcones (1,4-selectivity) and then into 1,3-diarylpropan-1-ols (C�O reduction). The stereoelectronic effects of electron-donating and electron-withdrawing groups at the ortho, meta and para positions of both aromatic rings were evaluated. The 2-OH group at the B ring was well tolerated, allowing a straightforward enantioselective synthesis of two flavans through the Mitsunobu cyclization, the antiviral (S)-BW683C and the natural flavan (S)-tephrowatsin E.

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