Enantioselective Reduction of Ketones Induced by a C₂‐Symmetrical Chiral Hydroxyamide/Titanium(IV) complex

Abstract

The asymmetric reduction of ketones catalyzed by chiral titaniumc omplex, prepared in situ from titaniumt etraisopropoxide and aC 2 -symmetrical chiral hydroxyamide, with catecholborane as the reducing agent afforded the corresponding chiral secondary alcohols in good yields with high enantioselectivity of up to > 99 % ee.

Ultrafast Iron‐Catalyzed Reduction of Functionalized Ketones: Highly Enantioselective Synthesis of Halohydrines, Oxaheterocycles, and Aminoalcohols

“…This development has been the focus of many recent studies in which the potential of 3d metals in enantioselective catalysis for the reduction of carbon–carbon and carbon–heteroatom multiple bonds has been reported . The majority of these studies is limited to simple diaryl, aryl alkyl, and dialkyl ketones as the substrates, with more complex structures being explored only in selected cases …”

Synthesis of C2-Symmetric Bisphosphines and Their Application in Enantioselective Transition Metal Catalysis

“…[21][22][23][24][25][26][27] The asymmetric transfer hydrogenation (ATH) or reduction of ketones allows the production of a large number of useful chiral alcohols that are ubiquitous in nature and are in great demand for flavors and fragrances, for pharmaceuticals, and for agrochemicals. [28][29][30][31][32][33][34][35] Apart from some procedures, ATH includes some interesting advantages such as using environmentally friendly solvents, low catalyst loading, safe application and volatile byproducts. Consequently, it can be easily applied to industrial processes.…”

Base-Free Dynamic Kinetic Resolution of Secondary Alcohols with a Ruthenium–Lipase Couple

“…37.2 mg (93% yield, >99% ee); [α] 25 D = +95.3 (c = 1.0, CHCl 3 ) [lit. 19 [α] 25 D = +103.0 (c = 1.05, CHCl 3 , 95% ee)]; 1 H NMR (CDCl 3 , 300 MHz): δ 7.36−7.22 (m, 4H), 5.88−5.82 (q, J = 6.6 Hz, 1H), 2.06 (s, 3H), 1.55−1.52 (d, J = 6.6 Hz, 3H); 13 C{ 1 H} NMR (CDCl 3 , 75 MHz): 172.0, 145.6, 136.3, 131.7, 129.9, 128.1, 126.1, 73.4, 24.1, 23.1; HPLC conditions: (R,R)-Whelk-O1, n-hexane/2-propanol = 90/10, flow rate = 0.5 mL/ min, UV = 217 nm; retention times: 8.01 min (S), 12.13 min (R). The NMR data are in good agreement with those reported in the literature.…”