Mechanistic insights into catalytic cyclopropanation by copper(I) phosphine complexes. X-ray crystal structures of [Cu(FBF3)(PCy3)2] (Cy = cyclo-C6H11) and [Cu(MeCN)2{1,2-C6H4CH2NMe2(PPh2)}]BF4

Catalytic cyclopropanation of olefins using copper(I) diphosphinoamines

“…Surprisingly the reaction with the perchlorate complex took almost 2 h to start, whereas the tetrafluoroborate complex initiated the reaction almost instantaneously. The tetrafluoroborate complex (2 mol%) studied by Woodward and coworkers gave 60% cyclopropane product from styrene in 10 min at ambient temperature and 30% cyclopropane product from cyclohexene in 10 min under similar conditions (entries 3 and 4) [2]. The complex [Cu(CH 3 CN) 4 ]B(C 6 F 5 ) 4 [8] has been reported to yield around 71% of cyclopropane product of styrene with 49:51 ratio of trans to cis cyclopropane (entry 5) when used in 2 mol% concentration.…”

“…Monodentate phosphines like PPh 3 , [2] PCy 3 , [2] PPh 2 -Ar, (Ar = o-Me 2 N-(CH 2 )-C 6 H 4 ), [2] diphosphines like (PPh 2 ) 2 (CH 2 ) 2 (dppe) [6e] have also been investigated for the catalytic reaction. With 2 mol% of the monophosphine catalyst, the cyclopropane was obtained in low yields (27-65%) (entries [6][7][8][9].…”

“…Transition metal catalyzed cyclopropanation reaction of olefins proceeds via cycloaddition of a metal-bound carbene fragment to an olefin (Scheme 1) [1][2][3]. A variety of transition metals promote the reaction, although copper and rhodium appear to be the best.…”

Cyclopropanation on a highly active heterogeneous catalyst: CuO/TiO2-Al2O3

“…Decreasing the addition rate of EDA to the reaction medium results in better cyclopropane yields. When a four-fold excess of styrene is used and the addition time is increased to 4 h, a yield of 93.5% is obtained on CuO/TiO 2 -Al 2 O 3 (12 wt.%) catalyst (see Table 3), which is even higher than those of many homogeneous copper-catalyzed cyclopropanation reactions [26,27]. These results suggest that the competitive adsorption between olefin and EDA is one of the reasons for the limited production of cyclopropanes.…”

BR2BodPR2: highly fluorescent alternatives to PPh3and PhPCy2

“…18 However, when the counter-ions tetrafluoroborate and perchlorate were employed, three-coordinate structures were obtained (similar to 5a, structure B) with copper-fluorine and copper-oxygen distances of 2.420(6) and 2.220(7) Å and P-Cu-P angles of 159.98(8)°and 144.46(6)°respectively. 23,24 Willet et al showed that dicyclohexylphenylphosphine (which is the closest analogue to 3a and 3b) produced [Cu(PCy 2 Ph) 2 ][ClO 4 ] with the perchlorate anion, but with tetrafluoroborate a different copper(I) complex formed, [Cu(PCy 2 Ph) 2 (F-BF 3 )]. Currently the crystal structures are not known to confirm whether the counter-ions have any significant coordinating interaction.…”