Heterodimerization of Olefins. 1. Hydrovinylation Reactions of Olefins That Are Amenable to Asymmetric Catalysis

Abstract

Through a systematic examination of ligand and counterion effects, new protocols for a nearly quantitative and highly selective codimerization of ethylene and various functionalized vinylarenes have been discovered. In a typical reaction, 4-bromostyrene and ethylene undergo codimerization in the presence of 0.0035 equiv each of [(allyl)NiBr]2, triphenylphosphine, and AgOTf in CH2Cl2 at -56 degrees C to give 3-(4-bromophenyl)-1-butene in >98% yield and selectivity. Corresponding reactions with [(allyl)PdX]2 are much less efficient and less selective and may require further optimization before a viable system can be identified. Another useful protocol that gives comparable yield and selectivity involves the use of a single-component catalyst prepared from allyl 2-diphenylphosphinobenzoate, Ni(COD)2, and (C6F5)3B. Recognition of a synergistic relationship between a chiral hemilabile ligand (for example, (R)-2-methoxy-2'-diphenylphosphino-1,1'-binaphthyl, MOP) and a highly dissociated counteranion (BARF or SbF6) in an enantioselective version of the Ni-catalyzed reaction raises the prospects of developing a practical route for the synthesis of 3-arylbutenes. Several pharmaceutically relevant compounds, including widely used 2-arylpropionic acids, can be synthesized from these key intermediates. This reaction appears to be quite general. Synthesis of several new 2-diphenylphosphino-1,1-binaphthyl derivatives, prepared to probe the effect of hemilabile coordination on the efficiency and selectivity of the reaction, are also described.

Convenient synthesis of tropos phosphine-oxazoline ligands

“…time, Pd-catalyzed insertion reactions of 4 with electrondeficient diarylphosphine oxides failed. Such result was also obtained in synthesis of other ligands [42]. But in many cases, enantioselectivity of asymmetric catalysis is affected dramatically by the substituents at the aryl groups of phosphine in the ligands.…”

Iodine‐ and PhI(OAc)2‐Mediated Multicomponent Synthesis of (E)‐1,3‐Diphenyl‐1‐butene Derivatives

“…[2][3][4] As a result, various reagent systems have been reported to effect the transformation, which include transition-metal-free acids such as AcClO 4 , [5] CF 3 SO 3 H, [5] zeolites, [1] pTsOH, [4] HClO 4 [4] and iodine [6] as well as transition-metal-based catalysts, namely [Ni(π-C 3 H 5 )(OCOCF 3 )] 2 , [7] (ally)Ni-I 2 , [8] [(η 3 -C 3 H 5 )Pd(CD 3 NO 2 ) 2 ]-(BF 4 ) [9] Co 2 (CO) 8 , [10] Pd(PPh 3 ) 2 (BF 4 ) 2 , [11] (ally)Ni-Cl 2 , [12] Pd(OAc) 2 / diazonium salt, [13] Pd( -diketonate) 2 /BF 3 ·OEt 2 , [14] Pd(OAc) 2 / In(OTf ) 3 , [15] Pd(OAc) 2 /Cu(OTf ) 2 /ionic liquid, [16] Ni(dppp)Cl 2 , [17] [(η 6 -C 6 H 6 )(PCy 3 )(CO)RuH] + BF 4 -, [18] Fe III salts, [3] [(acac)Pd(PAr 3 ) 2 ]-BF 4 /BF 3 ·OEt 2 , [19] Pd(acac) 2 /TFA, [2] (ally)Ni-NHC [20] and [AllylPd-(PPh 3 )] + OTf -. However, formation of 1,3-diphenyl-1-butenes by head-to-tail dimerization has received more attention than the others since it generates an allylic chiral centre, which is reported to be present in a number of biologically important organic molecules.…”

Ligandless Iron‐Catalyzed Desulfinylative C–C Allylation Reactions using Grignard Reagents and Alk‐2‐enesulfonyl Chlorides

“…gave the mixture of products (71 mg, 75 %) as a colorless oil. [41] and 1-(But-3-en-2-yl)-4-methylbenzene (Table 4, Entries 2 and 5): [42] Method A: Following the typical experimental procedure, sulfonyl chloride 3 (0.1 g, 0.65 mmol, 1 equiv.) and p-tolylmagnesium chloride (5b; 1.0  in THF, 1.0 mL, 1.0 mmol, 1.5 equiv.)…”