Page 782 - Advanced Organic Chemistry Part B - Reactions & Synthesis

758 1.8 mol % NiCl (dppp)
2
CHAPTER 8 (CH ) NCO 2 O CN(CH ) CH MgBr CH 3 CH 3 89%
3
2
3 2
3 2
Reactions Involving Ref. 271
Transition Metals
Vinyl carbamates are also reactive.
OTBDMS OTBDMS
Ni(acac) 2
+ RMgX
) CH
) CH
(CH 3 2 O CN[CH(CH ) ] (CH 3 2 R
2
3 2 2
CH 3 CH 3
R = CH = CH, Ph
2
Ref. 272
Similarly, nickel catalysis permits the extension of cross coupling to vinyl
phosphates, which are in some cases more readily obtained and handled than vinyl
triflates. 273
OPO(OPh) 2 Ni(dppe) Cl 2 Ph
2
1 mol %
+ PhMgBr
92%
Nickel acetylacetonate, Ni acac , in the presence of a styrene derivative promotes
2
coupling of primary alkyl iodides with organozinc reagents. The added styrene
serves to stabilize the active catalytic species, and of the derivatives examined,
m-trifluoromethylstyrene was the best. 274
O O
Ni(acac) 2
N CCH CH I + (n -C H ) Zn N C(CH ) CH 3
2 6
2
5 11 2
2
m-CF C H CH CH 2 70%
3 6 4
This method can extend Ni-catalyzed cross coupling to functionalized organometallic
reagents.
Nickel can also be used in place of Pd in Suzuki-type couplings of boronic acids.
The main advantage of nickel in this application is that it reacts more readily with aryl
chlorides 275 and methanesulfonates 276 than do the Pd systems. These reactants may be
more economical than iodides or triflates in large-scale syntheses.
Ni(dppf) Cl 2
2
4 mol %
CH 3 B(OH) + CH SO 3 CN CH 3 CN
3
2
3 equiv K 2 CO 3
97%
271
C. Dallaire, I. Kolber, and M. Gringas, Org. Synth., 78, 42 (2002).
272 F.-H. Poree, A. Clavel, J.-F. Betzer, A. Pancrazi, and J. Ardisson, Chem. Eur. J., 7553 (2003).
273
A. Sofia, E. Karlstom, K. Itami, and J.-E. Backvall, J. Org. Chem., 64, 1745 (1999); Y. Nan and
Z. Yang, Tetrahedron Lett., 40, 3321 (1999).
274 R. Giovannini, T. Studemann, G. Dussin, and P. Knochel, Angew. Chem. Int. Ed. Engl., 37, 2387
(1998); R. Giovannini, T. Studemann, A. Devasagayaraj, G. Dussin, and P. Knochel, J. Org. Chem.,
64, 3544 (1999).
275 S. Saito, M. Sakai, and N. Miyaura, Tetrahedron Lett., 37, 2993 (1996); S. Sato, S. Oh-tani, and
N. Miyaura, J. Org. Chem., 62, 8024 (1997).
276
V. Percec, J.-Y. Bae, and D. H. Hill, J. Org. Chem., 60, 1060 (1995); M. Ueda, A. Saitoh, S. Oh-tani,
and N. Miyaura, Tetrahedron, 54, 13079 (1998).