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J. Org. Chem. 1990,55, 6194-6198
sodium chloride solution (2 x 20 mL). The organic layer was dried over anhydrous MgS04, filtered through a small pad of silica gel, and concentrated by removal of the solvent through a 100-cm VilPux column* Remaining solvent W a s removed by Placing the oil under reduced pressure for short periods of time. Purification by bulb-to-bulb distillation gave dodecane (0.12 g, 76% yield) as a clear colorless oil. The purity of compounds 5 , 7, 11, and 13 was 195% as determined by GC and by 13C and 1H NMR determinations. GC retention times and all spectra were identical with those of commercial standards.
Acknowled~ent*We gratefully support for this research by the American cancer Society through a Univeristy Of Iowa/American cancer Society InStitUtional Research Grant and by the donors of the Petroleum Research Fund, administered by the American Chemical
Society. Palladium was generously loaned through the Johnson Matthey, Inc., Precious Metal Loan Program. We thank Professor Widdowson of Imperial College for sharing experimental details of his work. We also thank a referee for suggesting the CH,I,CH3CI trapping experiments. Registry No. 1,2050-77-3;4,143-15-7; 6,4119-41-9;8,637-59-2;
9, 104-52-9; 10, 40548-64-9; 12, 129848-86-8; 14, 59456-20-1; 20,
925-90-6; 21, 1462-75-5; PhMgBr, 100-58-3; MeMgC1, 676-58-4; (dppf)Pd(O),127140-10-7; (dppf)PdC12, 72287-26-4.
Supplementary Material Available: Spectral characteristics of compounds 5 , 7 , 10, 12, 13, and 14, the GC/MS data arising from the mixture obtained on reduction of 3-iodo-l-phenylbutane, more detailed experimental information for the reduction of iodides 12 and 14, and *Hand 3C NMR spectra of 11,12, and 14 (IOpages). Ordering information is given on any current masthead page.
New Desulfurizations by Nickel-Containing Complex Reducing Agents Sandrine Becker, Yves Fort, and Paul Caub6re* Laboratoire d e Chimie Organique I , U.R.A. C N R S No. 457,Synthese Organique et Bioingknkrie, Facult: des Sciences, Domaine Scientifique Victor Grignard, B.P. 239, 54506 Vandoeuvre-les-Nancy C k d e r , France R e c e i v e d A p r i l 17, 1990
Desulfurizations of saturated aliphatic or aromatic sulfoxides or sulfones are efficiently performed with nickel complex reducing agents (NiCRA’s). The complete desulfurization of dithioketals can be effected in high yields with these reagents, while their half-desulfurization is efficiently achieved with 2,2’-bipyridine-modified nickel complex reducing agents (NiCRA-bpy). The desulfurization of vinyl thioethers, sulfoxides, and sulfones have been shown to be chemoselective, leaving the C-C double bond intact. The desulfurization of (E)-PhS02(CH,)C=CHPh to cis-CH,CH=CHPh with NiCRA in the presence of quinoline is 95% enantioselective.
Introduction Desulfurization of organic compounds is important in the production of nonpolluting fuels and is also a cornerstone of organic synthesis using sulfur chemistry.’ Among numerous desulfurizing reagents, heterogeneous nickel reagents occupy an important position. A number of Raney nickels2v3and in situ generated nickel boride4 have been the most widely used nickel reagents. Drawbacks of Raney nickels include their tedious preparation, hazards in handling, difficulty in determining the weight of Ni, and the large Ni/S ratio nece~sary.~ Nickel boride is more convenient but less reactive. Both reagents suffer (1) (a) Eisch, J. J.; Hallenbeck, L. E.; Han, K. I. J . Org. Chem. 1983, 48,2963and references cited therein. (b) Eisch, J. J.; Hallenbeck, L. E.; Lucarrelli, M. A. Fuel 1985,64,440 and references cited therein. (c) Aitken, J.; Heeps, T.; Steedman, W. Fuel 1968,47,353. (2)(a) Pettit, G. R. In Organic Reactions, Vol. 12; Cope, A. C., Ed.; John Wiley and Sons, Inc.; 1966;p 356. (b) Hauptmann, H.; Walter, W. F. Chem. Reo. 1962,62,347. (c) Bonner, W.A.; Grimm, R. A. In The Chemistry of Organic Sulfur Compounds; Kharasch, N., Meyers, C. Y., Eds.; Pergamon Press: New York, 1966;Vol. 2, p 35. (d) Magnus, P. D. Tetrahedron 1977,33,2019.( e ) Trost, B. M. Chem. Reu. 1978,78,363. (0 Field, L. Synthesis 1978,713. ( 9 ) Dieter, R. K. Tetrahedron 1986,42, 3029. (h) De Lucchi, 0.;Pasquato, L. Tetrahedron 1988,44,6755. (3) (a) Mozingo, R.; Wolf, D. E.; Harris, S. A.; Folkers, K. J . Am. Chem. SOC.1943,65,1013. (b) Snyder, H. R.; Cannon, G. W. J . A m . Chem. SOC.1944,66,155. (c) Blicke, F. F.; Sheets, D. G. J. Am. Chem. SOC.1948,70,3768.(d) Latif, K. A.; Umor Ali, M. Indian J. Chem. 1984, 23B,471. (e) Dieter, K.; Lin, Y. J. Tetrahedron Lett. 1985,26,39. (f) Nagai, M.Chem. Lett. 1987,1023.(g) Nakyama, J.;Yamaoka, S.; Oshino, H. Tetrahedron Lett. 1988,29,1161. (h) Barton, D. H. R.; Britten-Kelly, M. R.; Ferreira, D. J . Chem. Soc., Perkin Trans. 1 1978,1090.
0022-3263/90/1955-6194$02.50/0
from a lack of chemo~electivity.~~~~ Literature data*,2b83”316 indicates that the desulfurizing properties of nickel reagents are mainly due to hydrogen adsorbed on the surface of the finely divided reagents and to single-electrontransfer (SET) ability. The easily prepared nonpyrophoric nickel-containing complex reducing agents (NiCRA’s and N~CRAL’S)’~ appeared interesting as new candidates for desulfurizing reagents, since they are strong “hydrogen transmitters” * and effect SET reaction^.^ These prop(4)(a) Truce, W. E.; Perry, F. M. J. Org. Chem. 1965,30, 1316. (b) Clark, J.; Grantham, R. K.; Lydiate, J. J. Chem. SOC.C 1968,1122. (c) Boar, R. B.; Hawkins, D. W.; McGhie, J. F.; Barton, D. H. R. J. Chem. Soc., Perkin Trans. I1973,654. (d) Sarma, D. N.; Sharma, R. P. Tetrahedron Lett. 1985,26,371.(e) Shut, J.; Engberti, J. B. F. N.; Wynberg, H. Synth. Commun. 1972,2,415.(f) Truce, W. E.; Perry, F. M. J. Org. Chem. 1966,30,1316. (g) Everby, M.R.; Waigh, R. D. Synth. Commun. 1986,16,779. (5)Truce, W. E.; Roberts, F. E. J. Org. Chem. 1963,28,961. Eisch, J. J.; Im, K. R. J. Organomet. Chem. 1977,139,‘251. (6)Padmanabhan, S.; Ogawa, T.; Suzuki, H. J. Chem. Research, Synop. 1989,266. Zaman Syed, S.;Parijat, S.; Nakin, C. B.; Ram, P. S. Chem. Ind. 1989,806. Ho, K. M.; Lam, C. H.; Luh, T. Y. J. Org. Chem. 1989,54,4474.Chan, M. C.; Cheng, K. M.; Ho, K. M. Ng, C. T.; Yam, T. M.; Wang, B. S. L.; Luh, T. Y. J. Org. Chem. 1988,53,4466. (7)(a) Caubere, P. Angew. Chem., Int. Ed. Engl. 1983,22,599.In this
paper we have adopted the following convention: a NiCRA prepared from NaH, t-AmONa, and nickel acetate is abbreviated NiCRA ( x / y / z ) , where x / y / z is the molar ratio NaH/t-AmONa/Ni(OAc),. In the same manner, a NiCRA-bpy prepared from NaH, t-AmONa, nickel acetate, and 2,2’-bipyridine is abbreviated NiCRA-bpy ( x / y / z / t ) , where x / y / z / t is the molar ratio NaH/t-AmONa/Ni(OA~)~/2,2’-bipyridine. (b) Aggregative activation (AA) covers all the phenomena occurring in complex bases and complex reducing agents and was introduced by P. Caub€re, 8th FECHEM on Organometallics, VESZPREM, Hungary, 8/1989. C 1990 American Chemical Society
J. Org. Chem., Vol. 55, No. 25, 1990
Desulfurizations by Ni-Containing Reducing Agents
-
6195
Table I. Desulfurization of Sulfoxides and Sulfones by NiCRA'sO R'S(0),RZ R'H or R1R2H2 1
run 1 2 3 4 5
R' CBHISC(CHB)H
R2 C2H5
C12H25 C12H25
C2H5 C12H25
(C&)zCH
C2H5
n
XIY/Zb
Nils'
t (h)
recvdd 1, %
71211 5/2/1 7/2/1 71211 41211
20 25 30 20 10
16.5 19 16.5 4 18
40
10
19
1 1 1 1 1
10
2
2
2: % 67 99 78
-
10 10
100 75f
8 I#
OReaction performed on I-mmol scale with NiCRA ( x / y / z ) in THF (50 mL) at 65 O C . *Ratio of NaH/RONa/Ni(OAc),. 'Atom Ni/atom S. dRecovered starting material determined by GC analysis. 'Yields based on sulfoxide or sulfone used and determined by GC analysis with comparison with authentic samples. !Reaction performed in DME at 65 " C with NiCRA-bpy (4/2/1/2). #Reaction performed in DME (50 mL) at 65 O C . Table 11. Half a n d Complete Desulfurization of Dithioketals by NiCRA's
3
4
run
R1
1 2 3 4 5 6 7 8 9 10 11 12
R2
R3
R'
Ni/S' 30 30 30 30 30 30 30 30 30 30 30 10
5
complete desulfurization t (h) recvdd 3% 4e % 1 17.5 1.25 1.5 17.5 17.5 10 17 2 1 6 4.25
0 35 0 0 0 4 4 20 0 12 0 19
100 100 99 90 99 100 100 100 95 98 99 100
Ni/SC 20 20 20 20 20 20 20 20 20 20 15 15
half desulfurization t (h) 5.C % . . recvdd 3. % 18 3 18 18 1 2 17 26 18 3.5 2 3.5
0 0 0 12 8 8 10 0 0 0 0 0
90 99 80 91 100 100 78 50 85
45 80 54
4.e % 10 20 9 22 50 13 55 20 46
'Reaction performed on I-mmol scale with NiCRA (5/2/1) in THF (50 mL) at 65 "C. bReaction performed on I-mmol scale with NiCRA-bpy (4121112) in DME (50 mL) at 65 "C. 'Atom Nilatom S. dRecovered starting material determined by GC analysis. eYields based on dithioketals used and determined by GC analysis with comparison with authentic samples. 4-tert-butyl-C6Hg 4-tert-butyl-CsHg 4tert-butyl-CBHQ4-tert-butyl-CBHQ
erties were attributed to Aggregative activation (AA)7b effects in these polymeric reagents. Our first experiments showed that NiCRA and NiCRA-bpy were efficient in desulfurizing aryl, heteroaryl, and alkyl thiols or thioethers.1° Moreover, we found that functions such as ketone or ester groups were tolerated. In this paper we wish to present the answer to the following questions: (i) Are NiCRA's able to desulfurize sulfoxides and sulfones? (ii) Are NiCRA's able to completely or half-desulfurize dithioketals? (iii) Do NiCRA's tolerate carbon-carbon double bonds?
Results and Discussion Desulfurization of Saturated or Aromatic Sulfoxides and Sulfones. In Table I we report the desul(8) (a) Fort, Y.; Vanderesse, R.; Caubere, P. Tetrahedron Lett. 1985, 26, 3111. (b) Fort, Y.; Vanderesse, R.; Caubere, P. Tetrahedron Lett. 1986,27,5487. (c) Fort,Y.; Vanderesse, R.; Caubere, P. Chem. Lett. 1988,
757. (d) Feghouli, A.; Fort, Y.; Vanderesse, R.; Caubere, P. Tetrahedron Lett. 1988, 29, 1379.
(9) Fort, Y. These d'Etat, Nancy, France, 1987. (10) (a) Becker, S.; Fort, Y.; Vanderesse, R.; CaubBre, P. Tetrahedron Lett. 1988, 29, 2963. (b) Fort, Y.;Becker, S.; Vanderesse, R.; Caubhre, P. 7the IUPAC Conference, Nancy, France, 1988. (c) Becker, S.; Fort, Y.; Vanderesse, R.; CaubBre, P. J. Org. Chem. 1989, 54, 4848.
furization of a number of representative sulfoxides and sulfones. It appears that with a few exceptions, yields of desulfurization products vary from good to excellent. Curiously, with dibenzothiophene oxide NiCRA-bpy led to better results than NiCRA. During the desulfurization of a number of sulfoxides or sulfones, we observed the intermediate formation of the corresponding sulfides. These observations could mean that reduction at the sulfur atom might be the first step in these reactions and that the actual desulfurization takes place on the correspondingthioethers. This possibility and its potential applications are presently being investigated. From a practical point of view, the above results show that NiCRA's are very convenient in the desulfurization of sulfoxides and sulfones. Desulfurization of Dithioketals. Considering the successful desulfurization of thioethers,'& we supposed that complete desulfurization of dithioketals would be possible if a sufficient amount of sodium hydride rich NiCRA was used. On the contrary, half-desulfurization, a reaction not easily performed with usual nickel reagents, would necessitate a weaker NiCRA containing less sodium hydride. From previous work we knew that NiCRAL (L = bpy or PPh3)were very poor reducing agents.7a Moreover, it could
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J. Org. Chem., Vol. 55, No. 25, 1990
Becker et al.
Table 111. Desulfurization of Vinyl Sulfides by NiCRA-bpy (2/2/1/2) in DME at 65 O C " R'
xsFp )=( R'
R'
R'
run 1
2 3 4 5 6 7 8 9
RZ
H
H H CH3 CH3
H
6
R3
C6H13 C6H13
H
R3
C5H11 C5Hll
C2H5
CH3 CH3
C2H5 C6H5 C2H5 C6H5
CsH5
C2H5
C6H5 C6H5
C6H5
+
H
7
Nilsb 10 20 20 20 10 10 20 10 10
C6H5
(CH2)lO (CH2)lO
CH3 CH3 CH3
R2
R'
H H
R1
~3
+
C6H5
)CHCH2R3 R2
8
t (h)
recvdc 6, % 15
18 17
17 17
5.5 20 18
27 18 24
4
18
10
7 ( E / Z ) , d70
94 90 97 (90/10) 98 (86/14) 99 (78/22) 99 (78/22) 92 78e 90 (82/8)f
8,d %
6 8 3 1
8 22
9
a Reaction performed on 1-mmol scale. bAtom Ni/atom S. 'Recovered starting material deteremined by GC analysis. dYields based on vinyl sulfide used and determined by GC analysis with comparison with authentic samples. e Reaction performed with NiCRA-bpy (4/2/ 1/2). fReaction performed with mixture E/Z = 60/40 of vinyl sulfide.
Table IV. Desulfurization of Vinyl Sulfoxides and Sulfones by NiCRA (2/2/1) in DME at 65 "C" R' )=
