Fe/Cr- and Co/Cr-Mediated Catalytic Asymmetric 2-Haloallylations of Aldehydes

Abstract

The first example to couple aldehydes and 3-bromo-2-halopropenes in a catalytic asymmetric manner is reported. The coupling reaction is effected by the use of a chiral sulfonamide-Cr complex (prepared in situ from 1d, CrBr3, Fe(III) or from Co(II), Et3N, and Mn), TMSCl, and 2,6-lutidine. The method reported here is operationally simple and scalable, furnishing 3-halohomoallylic alcohols with a synthetically useful level of enantiomeric excess.

Iron Catalysis in Organic Synthesis

“…975 The reaction was performed in the presence of 2,6-lutidine and an excess of trimethylsilyl chloride. The halogenated homoallylalcohols were obtained in good yields and with high enantiomeric excess.…”

Synthesis of Benzotriazine and Aryltriazene Derivatives Starting from 2‐Azidobenzonitrile Derivatives

“…[20] This compound was prepared from 2-amino-5-methylbenzonitrile (6c; [28] 3.40 g, 25.5 mmol) according to the procedure given for compound 4a. The product was obtained as a yellow solid (3.65 g, 91 %), m.p.…”

“…The combined organic solvents were washed several times with water, dried (Na 2 SO 4 ) and evaporated to afford 2-amino-5-methoxybenzonitrile (6b; 0. [28] This compound was prepared from p-toluidine in two steps according to ref. [28] The total yield of the desired product was (83 % 2-Amino-3,5-dimethylbenzonitrile (6d): [29] This compound was prepared from 2,4-dimethylaniline (9.8 g, 80.9 mmol) in two steps according to ref.…”

“…[28] This compound was prepared from p-toluidine in two steps according to ref. [28] The total yield of the desired product was (83 % 2-Amino-3,5-dimethylbenzonitrile (6d): [29] This compound was prepared from 2,4-dimethylaniline (9.8 g, 80.9 mmol) in two steps according to ref. [29] The product was obtained as a dark-brown oil (4.8 g, 41 % [30] This compound was prepared from 2-aminobenzonitrile (6a; 5.0 g, 42.4 mmol) and N-chlorosuccinimide (NCS; 5.93 g, 44.4 mmol) according to ref.…”

Nickel‐Catalyzed Intramolecular C−O Bond Formation: Synthesis of Cyclic Enol Ethers

“…In addition to simple vinyl iodides (e.g., 4b , R 1 = Me, R 2 = H, R 3 = H), [18] a ( Z )-styrenyl iodide (i.e., 4c , R 1 = Me, R 2 = H, R 3 = Ph) [19] furnished vinyl ether 5c in high yield and without loss of olefin stereochemical fidelity. Aminocyclohexanols bearing isopropyl and allyl substituents on nitrogen afforded the corresponding products in reduced yields ( 5d and 5e ).…”