Aldrichimica Acta - Sigma-Aldrich

80
VOL. 42, NO. 3 • 2009 Synthesis and Applications of Diorganozinc Reagents: Beyond Diethylzinc
(a)
(b)
R 2
R 1 CO 2R 3
Ph
O
O
N
Ph
O
1. (R4 ) 2Zn, CuI or
CuCN (20 mol %)
PhMe, 0 °C to rt
3–15 h
2. H + or E +
R1 CO2R3 R4 R
E
2
61–85%
dr >83:17
R 1 = H, Me, Ph, PhMe 2Si; R 2 = H, n-C 6H 13
R 3 = Me, Et; R 4 = Me, Et, i-Pr, Ph, 2-MeC 6H 4, H 2C=CH
O
Ph
1. Et2Zn (4 equiv)
CuBr•SMe2 (20 mol %)
MgBr2•OEt2 PhMe, –78
Ph
Et
N
O
E
dr >95:5
O
E = H (82%), I (66%), allyl (65%)
oC 2. H + or E +
Scheme 15. Copper-Catalyzed, directed Carbozincation of
Cyclopropene derivatives with diorganozinc reagents. (Ref. 94)
OMe
N
ClCO 2Bn
(4 equiv)
THF, 0 °C
0.5 h
BnO
SPh
O
O
SPh
P N
OMe
N
Cl
O
–
+
1. R2Zn (2.5 equiv)
16 (10 mol %)
Cu(OTf) 2 (5 mol %)
THF, –78 °C, 16 h
2. HCl(aq)
(16)
4. Conclusions and Outlook
Diorganozinc reagents are versatile nucleophiles that accommodate
either Lewis base or metal catalysis in enantioselective additions
to electrophiles. They also display a very high functional-group
tolerance. While a large number of diorganozinc reagents are now
readily available via simple procedures, and despite tremendous
improvements in accessing functionalized diorganozincs, as
pioneered by Knochel, Seebach, Bolm, and others, there is still a
strong need to increase their availability, which should significantly
enhance their usefulness in synthesis.
It is worth mentioning that diorganozinc reagents have several
other applications in organic synthesis, which have not been covered
in this review. These include the Negishi coupling, 96 oxidation to
alcohols, 97 addition to anhydrides 98 or acylation, 99 cyclopropanation
or epoxide formation (with carbenoids), 100 and the allylzincation of
alkenylmetals. 101
5. Acknowledgements
This work was supported by NSERC (Canada), the Canada Research
Chairs Program, the Canada Foundation for Innovation and the
University of Montréal. Alexandre Côté is grateful to NSERC (ES
D) for a postgraduate fellowship.
6. References and Notes
(1) For a recent publication on the properties, synthesis, and
applications of organozinc reagents, see The Chemistry of
Organozinc Compounds; Rappoport, Z., Marek, I., Eds.; The
R
Et
n-Pr
i-Pr
n-Bu
Ph(CH2) 2
O
N
BnO O
Yield
69%
65%
65%
63%
50%
ee
R
95%
88%
56%
93%
97%
Scheme 16. addition of dialkylzinc reagents to N-acylpyridinium
salts. (Ref. 95)
Chemistry of Functional Groups Series; Rappoport, Z., Series
Ed.; Wiley: Hoboken, NJ, 2006; Volumes 1 and 2.
(2) (a) Boezio, A. A.; Pytkowicz, J.; Côté, A.; Charette, A. B. J. Am.
Chem. Soc. 2003, 125, 14260. (b) Desrosiers, J.-N.; Côté, A.;
Boezio, A. A.; Charette, A. B. Org. Synth. 2006, 83, 5.
(3) For reviews on the synthesis of diorganozincs, see: (a) Knochel,
P.; Singer, R. D. Chem. Rev. 1993, 93, 2117. (b) Knochel, P.;
Leuser, H.; Gong, L.-Z.; Perrone, S.; Kneisel, F. F. Functionalized
Organic Compounds. In The Chemistry of Organozinc
Compounds; Rappoport, Z., Marek, I., Eds.; The Chemistry of
Functional Groups Series; Rappoport, Z., Series Ed.; Wiley:
Hoboken, NJ, 2006; Part 1, Chapter 8, p 287. (c) Knochel, P.;
Leuser, H.; Gong, L.-Z.; Perrone, S.; Kneisel, F. F. Polyfunctional
Zinc Organometallics for Organic Synthesis. In Handbook of
Functionalized Organometallics: Applications in Synthesis;
Knochel, P., Ed.; Wiley-VCH: Weinheim, 2005; Vol. 1, Chapter
7, p 251. (d) Knochel, P.; Millot, N.; Rodriguez, A. L.; Tucker, C.
E. Org. React. (NY) 2001, 58, 417. (e) Boudier, A.; Bromm, L. O.;
Lotz, M.; Knochel, P. Angew. Chem., Int. Ed. 2000, 39, 4414. (f)
Knochel, P.; Almena Perea, J. J.; Jones, P. Tetrahedron 1998, 54,
8275. (g) Knochel, P.; Jones, P.; Langer, F. Organozinc Chemistry:
An Overview and General Experimental Guidelines. In Organozinc
Reagents: A Practical Approach; Knochel, P., Jones, P., Eds.; The
Practical Approach in Chemistry Series; Harwood, L. M., Moody,
C. J., Series Eds.; Oxford University Press: Oxford, 1999, p 1. (h)
Knochel, P. Product Class 1: Organometallic Complexes of Zinc.
In Compounds of Groups 12 and 11 (Zn, Cd, Hg, Cu, Ag, Au);
O’Neil, I., Ed.; Science of Synthesis: Houben-Weyl Methods of
Molecular Transformations Series; Thieme: Stuttgart, 2003; Vol.
3, p 5.
(4) (a) Côté, A. Additions catalytiques énantiosélectives de réactifs
diorganozinciques utilisant un ligand diphosphine monoxydé. Ph.D.
Thesis, University of Montréal, Montréal, Canada, September
2007. (b) Charette, A. B.; Côté, A. Methods for Preparing
Diorganozinc Compounds. World Patent WO/2008/134890. (c)
Charette, A. B.; Côté, A.; Lemire, A. Methods for Preparing
Diorganozinc Compounds. U.S. Patent Appl. 12/591,108, Nov. 9,
2009.
(5) For other examples, see: (a) Corey, E. J.; Hannon, F. J. Tetrahedron
Lett. 1987, 28, 5237. (b) Bolm, C.; Rudolph, J. J. Am. Chem. Soc.
2002, 124, 14850. (c) Jeon, S.-J.; Li, H.; García, C.; LaRochelle, L.
K.; Walsh, P. J. J. Org. Chem. 2005, 70, 448. (d) Kim, J. G.; Walsh,
P. J. Angew. Chem., Int. Ed. 2006, 45, 4175. (e) Salvi, L.; Kim, J.
G.; Walsh, P. J. J. Am. Chem. Soc. 2009, 131, 12483.
(6) (a) Von Frankland, E. Justus Liebigs Ann. Chem. (Eur. J. Org.
Chem.) 1849, 71, 171. (b) Freund, A. Justus Liebigs Ann. Chem.
(Eur. J. Org. Chem.) 1861, 118, 1. (c) Rieth, R.; Beilstein, F. K.
Justus Liebigs Ann. Chem. (Eur. J. Org. Chem.) 1863, 126, 241. (d)
Pawlow, D. Justus Liebigs Ann. Chem. (Eur. J. Org. Chem.) 1877,
188, 104. (e) Wagner, G.; Saytzeff, A. Justus Liebigs Ann. Chem.
(Eur. J. Org. Chem.) 1875, 175, 351.
(7) (a) Schlenk, W.; Schlenk, W., Jr. Ber. Dtsch. Chem. Ges. B (Eur.
J. Inorg. Chem.) 1929, 62, 920. (b) Schlenk, W., Jr. Ber. Dtsch.
Chem. Ges. B (Eur. J. Inorg. Chem.) 1931, 64, 736. (c) Noller, C.
R.; White, W. R. J. Am. Chem. Soc. 1937, 59, 1354.
(8) For the synthesis of diethyl-, dipropyl-, dibutyl-, and diisoamylzinc,
see: (a) Noller, C. R. J. Am. Chem. Soc. 1929, 51, 594. (b) Noller,
C. R. Org. Synth. 1932, 12, 86 (Organic Syntheses; Blatt, A. H.,
Ed.; Wiley: New York, 1943; Collect. Vol. II, p 184). (c) Eremeev,
I. V.; Danov, S. M.; Sakhipov, V. R.; Skudin, A. G. Russ. J. Appl.
Chem. 2001, 74, 1410. (d) For the synthesis of dipentyl-, dihexyl-,
and diheptylzinc, see Hatch, L. F.; Sutherland, G.; Ross, W. J. J.
Org. Chem. 1949, 14, 1130. (e) For the synthesis of diisopropyl-