[(−)‐diop]RhCl—Catalyzed Asymmetric Addition of Bromotrichloromethane to Styrene

Catalytic Synthesis and Antifungal Activity of New Polychlorinated Natural Terpenes

“…The addition of tetrachloromethane to unsaturated terpenes can be obtained by treatment with CCl 4 , Fe(acac) 2 as catalyst, and NEt 3 in dry acetonitrile at 80 ∘ C. A possible mechanism for Kharasch reaction is shown in Scheme 1. As proposed by Murai et al [30] and Kameyama and Kamigata [31] in ruthenium catalyzed Kharasch reaction, we can assume that low-valent iron species probably react in a similar way as Ru II catalysts. At this stage, we cannot exclude a multiple-step process that involves radical intermediates as described by Oldroydg et al [29].…”

Chiral (–)‐DIOP Ruthenium Complexes for Asymmetric Radical Addition and Living Radical Polymerization Reactions

“…All of the chiral complexes preferably provided the (+)-enantiomer, which corresponds to the (R)-isomer in absolute configuration. [5] Furthermore, the enantiomeric selectivity with 1 and 2 increased by lowering the temperature, and the adduct obtained with 1 at 0°C showed the highest enantiomeric ex-cess (32 % ee) with a high chemical yield (Ͼ99 %). The optical yield was comparable to that of the rhodium-catalyzed asymmetric addition (32 % ee), whereas the chemical yield was much higher than that of the Rh-catalyzed reaction (26 %).…”

“…The optical yield was comparable to that of the rhodium-catalyzed asymmetric addition (32 % ee), whereas the chemical yield was much higher than that of the Rh-catalyzed reaction (26 %). [5] Indenyl ruthenium complex 2 was also effective in asymmetric radical addition reactions, although the activity was lower than that of 1. [b]…”

“…[2,3] However, the asymmetric radical addition reactions were rather limited except for a few examples. [4][5][6][7][8] The first relevant metal-catalyzed asymmetric halogen transfer radical addition reactions were reported with chiral ruthenium complexes bearing (+) or (-)-DIOP ligands [DIOP = 2,3-(isopropylidenedioxy)-2,3-dihydroxy-l,4-bis(diphenylphosphanyl)butane], which induced asymmetric radical addition reactions between arenesulfonyl chlorides (RSO 2 Cl) and styrenes (CH 2 =CHC 6 H 4 RЈ) to give optically active adducts (20-40 % ee) and relatively high chemical yields (40-100 %), both of which were dependent on the substituents (R and RЈ) and the reaction conditions.…”

“…Another precedent result was reported in 1981, in which a rhodium complex with a (-)-DIOP ligand, RhCl[(-)-DIOP], induced the asymmetric addition between bromotrichloromethane (CCl 3 Br) and styrene in 32 % ee and 26 % yield although the authors did not suggest a radical reaction. [5] Other asymmetric halogen transfer reactions were finely performed for more complex substrates by using chiral Lewis acids in the presence of a free radical initiator or by using chiral auxiliaries in an olefin to produce enantio-or diastereoselective products, respectively. [4,7,8] Another recently developed area in controlled radical reactions is the metal-catalyzed living radical polymerization or atom transfer radical polymerization (ATRP) that can precisely control the molecular weights and the terminal groups, which can be further applied to a wide variety of functional materials based on controlled polymer structures.…”