C O M M U N I C A T I O N S
Table 1. Reactions of 1,3-Dicarbonyl Phenyl Iodonium Ylides 1a
and 1b with Benzyl, Allyl, and Aryl Halides Using Rh2(OAc)4
Catalysisa
Supporting Information Available: Additional experimental details.
This material is available free of charge via the Internet at http://
pubs.acs.org.
References
(1) (a) Olah, G. A.; Bollinger, J. M. J. Am. Chem. Soc. 1967, 89, 4744. (b)
Olah, G. A.; DeMember, J. R. J. Am. Chem. Soc. 1970, 92, 718. (c) Olah,
G. A. Halonium Ions; Wiley-Interscience: New York, 1975. (d) Nesmey-
anov, A. N.; Makarova, L. G.; Tolstaya, T. P. Tetrahedron 1957, 1, 145.
(e) Koser, G. F. The Chemistry of Halides, Pseudo-halides and Azides;
Wiley-Interscience: Chichester, U.K., 1983; p 721.
(2) Lee, Y. R.; Jung, Y. U. J. Chem. Soc., Perkin Trans. 1 2002, 1309.
(3) The Stevens rearrangement of alkyl iodonium ylides is known: (a) Olah, G. A.;
Doggweiler, H.; Felberg, J. D. J. Am. Chem. Soc. 1985, 107, 4975. A 1,2
migration has been reported in the reaction of phenyliodonium bis(phe-
yieldb (%)
entry
ylide
R3-X
R4
X
3
nylsulfonyl)methylide with alkyl iodides. (PhSO2)2CdIPh
f
(PhSO2)2CICH2R: (b) Gogonas, E. P.; Nyxas, I.; Hadjiarapoglou, L. P.
Synlett 2004, 2563. Chloronium and bromonium ylides have been made
by the thermal decomposition of 3,5-dicyanodiazoimidazole in chloroben-
zene or bromobenzene: (c) Sheppard, W. A.; Webster, Q. J. Am. Chem.
Soc. 1973, 95, 2695.
1
2
3
4
5
6
7
8
9
1a 1b C6H5CH2Cl
1a 1b 3-MeC6H4Cl
1a 1b C6H5CH2Br
1a 1b 3-MeC6H4Br
1a 1b C6H5(CH3)CHCl
1b (S)-Ph(CH3)CHCl
C6H5CH2
3-MeC6H4
C6H5CH2
3-MeC6H4
C6H5(CH3)CH
(S)-Ph(CH3)CH Cl
Cl
Cl
Br
Br
Cl
70(a) 73(b)
62(c) 70(d)
22(e) 35(f)
30(g) 35(h)
53(i) 58(j)
58(k)
56(l)
37(m)
60(n) 63(o)
(4) (a) Spyroudis, S.; Tarantili, P. J. Org. Chem. 1993, 58, 4885. (b) Hayasi,
Y.; Okada, T.; Kawanish, M. Bull. Chem. Soc. Jpn. 1979, 43, 2506. (c)
Kokil, P. B.; Nair, P. M. Tetrahedron Lett. 1977, 18, 113. (d) Spyroudis,
S.; Varvoglis, A. J. Chem. Soc., Perkin Trans. 1 1984, 135. (e) Georgantji,
A.; Spyroudis, S. Tetrahedron Lett. 1995, 36, 443. (f) Moriarty, R. M. J.
Org. Chem. 2005, 70, 2893.
1a
1a
CH3C(CH3)CHCH2Cl CH2CH(CH3)2C Cl
CH2CHCH(Cl)CH3 CH3CHCHCH2 Cl
CH2CH(CH3)CH Cl
1a 1b CH3CHCHCH2Cl
10 1a 1b C6H5F
11 1a 1b C6H5Cl
12 1a 1b C6H5Br
13 1a 1b C6H5I
H
H
H
H
4-FC6H4 22(p) 30(q)
4-ClC6H4 41(r) 38(s)
4-BrC6H4 27(t) 37(u)
(5) The synthetic value of 2-halo-3-alkoxyenones is that they potentially offer a
highly functionalized substrate for syntheses using palladium coupling.
Compound 4 yields the tricyclic benzofuran system upon intramolecular Heck
reaction: Ma, D.; Cai, Q.; Xie, X. Synlett 2005, 11, 1767. See also: (a)
Liebeskind, L. S.; Wang, J. Tetrahedron Lett. 1990, 31, 4293. (b) Negishi,
E.; Owczarczyk, Z. R.; Swanson, D. R. Tetrahedron Lett. 1991, 32, 4453.
(c) Kabat, M.; Kiegiel, J.; Cohen, N. K.; Toth, P.; Wovkulich, M.;
Uskokovic, M. R. Tetrahedron Lett. 1991, 32, 2343. (d) Johnson, C. R.;
Adams, J. P.; Braun, M. P.; Senanayake, C. B. W. Tetrahedron Lett. 1992,
33, 919. (e) Johnson, C. R.; Braun, M. P. J. Am. Chem. Soc. 1993, 115,
11014. (f) Johnson, C. R.; Harikrishnan, L. S.; Golebiowski, A. Tetrahedron
Lett. 1994, 35, 7735. (g) Johnson, C. R.; Adams, J. P.; Collins, M. A.
J. Chem. Soc., Perkin Trans. 1 1993, 1.
4-IC6H4
30(v) 38(w)
a Conditions: Phenyliodonium ylide 1a or 1b (1 equiv)/alkyl, allyl, or aryl
halide (10 equiv), Rh2(OAc)4 (0.01 equiv)/Ar. b Isolated yields.
Scheme 5
(6) Rearrangement 1 to 4 regiochemically is an ipso process.4b
(7) A similar arylation reaction has been observed in the rhodium carboxylate
catalyzed reaction of 2-diazo-1,3-cyclohexanedione with fluorobenzene.
2-(4-Fluorophenyl)-1,3-cyclohexanedione was obtained. Pirrung, M. C.;
Zhang, J.; Lackey, K.; Sternbach, D. D.; Brown, F. J. Org. Chem. 1995, 60,
2112.
(8) Equal amounts of benzyl chloride and 3-methylbenzyl bromide were reacted
with 5,5-dimethyl-1,3-cyclohexanedione phenyliodonium ylide (1b) using 0.01
equiv of Rh2(OAc)4 under the standard conditions. Using HRMS, only masses
corresponding to 2-chloro-5,5-dimethyl-3-benzyloxycyclohex-2-enone and
2-bromo-5,5-dimethyl-3-(3-methylbenzyloxy)cyclohex-2-enone were detected.
No crossover products, 2-chloro-5,5-dimethyl-3-(3-methylbenzyloxy)cyclohex-
2-enone and 2-bromo-5,5-dimethyl-3-benzyloxycyclohex-2-enone, were de-
tected.
(9) (R)-R-Phenethanol [R]D ) 44.0 (neat) was obtained from Alfa-Aesar and was
converted to (S)-R-phenethyl chloride (5) [R]D ) 84.5 (c ) 5.4 CHCl3) using
POCl3/Pyr. Burwell, R. I.; Shields, A. D.; Hart, H. H. J. Am. Chem. Soc.
1954, 76, 908. The starting optical purity determined by chiral gas
chromatography was 87% S, 13% R. The yield of 6 was 78.6% S, 21.4%
R determined by chiral HPLC. Hydrolysis of 6 was nontrivial. Several
standard acid-catalyzed ether cleavage reactions proceeded with benzylic
oxygen cleavage. Method 6 to 7 to 8 (Scheme 2) is uniquely suited for the
present case and to the best of our knowledge is a novel process.
(10) Rhodium was not included in the calculations.
(11) (a) Bakalbassis, E. G.; Spyroudis, S.; Tsiotra, E. J. Org. Chem. 2006, 71,
7060–7062. (b) Gu, S. Y.; Su, M. D. J. Phys. Chem. A 2007, 111, 6587–
6591.
(12) An iodonio-Claisen process has been reported: (a) Ochiai, M.; Ito, T. J. Org.
Chem. 1996, 60, 2274–2275. (b) Ochiai, M.; Ito, T. J. Org. Chem. 1995,
70, 2274. (c) Ochiai, M.; Ito, T.; Masaki, Y. J. Chem. Soc.,Chem. Commun.
1992, 1, 15. (d) Ochiai, M.; Ito, T.; Takaoka, Y.; Masaki, Y. J. Am. Chem.
Soc. 1991, 113, 1319.
sigmatropic nature of 1 to 3, it was anticipated that allyl halides would
behave similarly. Accordingly, we discovered the novel chloronio-
Claisen rearrangement of the chloronium ylide (entries 7-9).12
The Claisen-type process can be described as shown in Scheme 4,
which accounts for the observed regiochemistry.
Finally, we investigated the reaction of aryl halides with 1a and 1b
under standard rhodium(II) conditions with the expectation of obtaining
the corresponding aryl halonium ylides via a process analogous to 1
to 2.13a,b
In fact, only electrophilic aromatic substitution was observed,
possibly via the intermediacy of 13 formed by electrophilic addition
of the Rh(II) carbenoid to the electron-rich substituted aromatic ring
(Scheme 5).14
(13) (a) Moriarty, R. M.; Bailey, B. R., III; Prakash, O.; Prakash, I. J. Am. Chem.
Soc. 1985, 107, 1375. (b) Yang, R.-Y.; Dai, L.-X.; Chem, C. G. J. Chem.
Soc., Chem. Commun. 1992, 1487.
(14) For a discussion of the formation of intermediates analogous to 11 formed
from Rh(II) catalytic decomposition of R-diazodicarbonyl compounds, see:
(a) Taber, D. F.; Hennessy, M. J.; Hoerrner, R. S.; Raman, K.; Ruckle, R. E.,
Jr.; Schuchardt, J. S. Catalysis of Organic Reactions; Blackburn, D. W.,
Ed.; Dekker: New York, 1990; Chapter 4, p 43. (b) Taber, D. F.; Ruckle,
R. E., Jr J. Am. Chem. Soc. 1986, 108, 7686.
In summary, this work advances our understanding of the unstable
and elusive chloronium and bromonium ylides and suggests the
application of this chemistry to obtain valuable synthetic building
blocks.
Acknowledgment. We dedicate this work to Professor E. J. Corey
on the occasion of his 80th birthday. Also we thank Professor Daesung
Lee of this department for insightful discussions.
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