Asymmetric addition of dimethylzinc to alkylidenmalonates mediated by phosphorous ligands: A new synthetic route to floral fragrances

Abstract

Six new phosphite ligands were prepared and their efficiency as chiral ligands was investigated in the copper-catalyzed asymmetric conjugate addition of dimethylzinc to diethyl 3-phenylpropylidenmalonate (5), affording the addition product with ees up to 74%. Moreover, a simple and straightforward route to floral fragrances Phenoxanol, Citralis, and Nitrile Citralis in optically active form through the above cited reaction was proposed.

Peptide‐Catalyzed Regio‐ and Enantioselective Reduction of α,β,γ,δ‐Unsaturated Aldehydes

“…Even when a mixture of four geometric isomers was used, the reaction still proceeded in a highly regio-and enantioselective manner ( Table 2, entry 4). Compared to the reports for the synthesis of these compounds, [27] the present regio-and enantioselective reaction offers a simpler synthetic pathway. As a demonstration, fragrance compounds, Citralis and Phenoxanol, were synthesized according to Scheme 1.…”

Using NMR Spectroscopy and Chemical Synthesis to Establish Diastereoselectivity of NaBH4 and Meerwein–Ponndorf–Verley (MPV) Reduction of (±)-Benzoin Isopropyl Ether: A Collaborative Discovery-Based Laboratory Experiment

“…After an aqueous workup, the product was extracted into CH 2 Cl 2 , dried, and rotary evaporated affording the crude product (avg yield = ∼100%). Reduction of 3 with DIBAL-H was also achieved by adaptation of a known procedure: a solution of 3 (0.39 mmol) in dichloromethane (2 mL) and DIBAL-H (2 mL, 1 M in CH 2 Cl 2 ) was stirred for 30 min. After an aqueous workup, the product was extracted into CH 2 Cl 2 , dried, and rotary evaporated (avg yield = ∼70%).…”

5,5,7,7-Tetrametyl-6,7-dihydro-5H-dibenzo[c,e]azepine

“…Dibenz[c,e]azepines constitute an important class of compounds widely employed as chiral or pro-chiral scaffolds for the construction of chiral catalysts for asymmetric synthesis or probes for chiral molecular recognition. In particular, 1,1 -binaphthylazepines have been widely employed as chiral ligands in organometallic catalysis [1][2][3][4][5] and organocatalysis [6][7][8][9][10], while not-atropisomerically stable (i.e., tropos) 1,1 -biphenylazepines have been reported both as structural motifs for the construction of the chiral ligands [9][10][11][12][13][14][15] and as the chiroptical probes for the absolute configuration assignment to the chiral acids [16][17][18][19] and amines [14,20]. In fact, in 1,1 -biphenylazepines the low phenyl-phenyl rotational barrier allows, at room temperature, a free interconversion of the two possible M and P atropisomeric forms.…”