N. Stuhr-Hansen / Tetrahedron Letters 46 (2005) 5491–5494
AcS
5493
SAc
i. n-BuLi, THF
ii. Et2NCO2Et 14
iii. H2O
AcCl/BBr3
(84%)
Ti(0)
10
S
Br
9
(76%)
13
AcS
SAc
15
Scheme 1.
resulting purple solution was poured into water and
extracted with ether–toluene (1:1, 3 · 25 mL). The pooled
organic extracts were filtered through basic alumina (10 g)
by means of ether–toluene (1:1) and evaporated. Com-
pound 10: Recrystallization from toluene gave (1.13 g,
82%) as white crystals. Mp: 232–233ꢁC. Anal. Calcd for
C42H52S4: C, 73.63; H, 7.65. Found: C, 73.28; H, 7.65. 1H
NMR (300 MHz, CDCl3): d 1.23 (s, 36H), 6.97 (d,
J = 7.9 Hz, 8H), 7.26 (d, J = 7.9 Hz, 8H). 13C NMR
(75 MHz, CDCl3): d 30.83, 45.72, 131.15, 131.33, 136.63,
140.06, 143.28. MS (EI, 70 eV) m/e (relative intensity): 684
(M+, 100), 628 (13), 572 (8), 516 (7), 460 (48).
The novel, acetyl protected, four terminal tetraphenyl-
ethylene thiol 15 has been incorporated in our recent
work as a component in molecularly based nanoscale
electronic devices. Due to its rigidity, 15 might be
applied to fixation of a gold cluster at each of the four
terminals.17 Electron transport studies on 15 will be
the subject of future investigations similar to those
recently carried out on OPVs.18
In summary, we have extended the use of microwaves in
organic synthesis to the McMurry reaction. Utilizing
microwave conditions, the McMurry reactions were
complete within 10 min. This method has been
employed in the synthesis of two- and four-terminal
molecular wires for molecular electronics.
10. Elandaloussi, E. H.; Frere, P.; Richomme, P.; Orduna, J.;
Garin, J.; Roncali, J. J. Am. Chem. Soc. 1997, 119, 10774.
11. Butula, I.; Curkovic, L.; Prostenik, M. V.; Vela, V.;
Zorko, F. Synthesis 1977, 704.
12. Procedure for the synthesis of 9: 4-Bromophenyl tert-butyl
sulfide 13 (34.3 g, 140 mmol) was added dropwise under an
argon atmosphere to a solution of n-butyllithium (2.5 M in
hexanes, 70 mL, 70 mmol) in THF (100 mL) cooled in a
dry ice/acetone bath. After stirring the reaction mixture at
ꢂ78ꢁC for 15 min, ethyl N,N-diethylcarbamate 14 (10.2 g,
70 mmol) was added over a 10-min period in a dropwise
fashion. The reaction mixture was stirred at room temper-
ature for 30 min and then poured into ice (300 g). THF was
gently removed on a rotary evaporator and a white product
was filtered off and dried in a vacuum oven (1mmHg,
100ꢁC). Recrystallization from heptane afforded 9 (19.1 g,
76%) as white needles. Mp: 152–153ꢁC. Anal. Calcd for
C21H26OS2: C, 70.35; H, 7.31; S, 17.88. Found: C, 70.29; H,
7.30; S, 17.93. 1H NMR (300 MHz, CDCl3): d 1.34 (s,
Acknowledgements
This research was supported by EC FP6 funding (con-
tract no. FP6-2004-IST-003673, CANEL). This publica-
tion reflects the views of the author and not necessarily
those of the EC. The Community is not liable for any
use that may be made of the information contained
herein.
References and notes
18H), 7.64 (d, J = 6.4 Hz, 4H), 7.75 (d, J = 6.4 Hz, 4H). 13
C
1. (a) Gedye, R.; Smith, F.; Wastaway, K.; Ali, H.; Baldi-
sera, L.; Laberge, L.; Rousell, J. Tetrahedron Lett. 1986,
27, 279; (b) Giguere, R. J.; Bray, T. L.; Duncan, S. M.;
Majetich, G. Tetrahedron Lett. 1986, 27, 4945.
2. Kappe, C. O. Angew. Chem., Int. Ed. 2004, 4, 1337.
3. Lidstrom, P.; Tierney, J.; Wathey, B.; Westman, J.
Tetrahedron 2001, 57, 9225.
4. McMurry, J. E.; Fleming, M. P. J. Am. Chem. Soc. 1974,
96, 4708.
5. Stuhr-Hansen, N. Synth. Commun. 2003, 33, 641.
6. Stuhr-Hansen, N.; Christensen, J. B.; Harrit, N.; Bjørn-
holm, T. J. Org. Chem. 2003, 68, 1275.
NMR (75 MHz, CDCl3): d 30.99, 46.76, 129.72, 136.52,
136.95, 138.66, 195.52. MS (EI, 70 eV) m/e (relative
intensity): 358 (M+, 8), 302 (16), 246 (100).
13. Prakash, G. K. S.; York, C.; Liao, Q.; Kotian, K.; Olah,
G. A. Heterocycles 1995, 40, 79.
14. Procedure for the synthesis of 14: Diethylcarbamoyl
chloride (21.1 g, 200 mmol) was added to a cooled mixture
of triethylamine (50 mL) and absolute ethanol (200 mL)
over a 10-min period in a dropwise fashion. The reaction
mixture was stirred at room temperature for 2 h and then
poured into ice (600 g) and extracted with pentane
(3 · 100 mL). The pooled organic phases were washed
with water (15 mL), dried with MgSO4, filtered, and
concentrated by rotary evaporation (30ꢁC, 20mmHg).
Bulb-to-bulb distillation (12mmHg, 100ꢁC) afforded 14
(16.8 g, 58%) as a colorless liquid. Purity >98% (GC–MS).
MS (EI, 70 eV) m/e (relative intensity): 145 (M+, 4), 135
(50), 120 (71), 100 (100).
7. A CEM925110 Discover microwave oven was used.
8. Rele, S.; Talukdar, S.; Banerji, A.; Chattopadhyay, T.
J. Org. Chem. 2001, 66, 2990.
9. Typical procedure: In a sealed tube, titanium(IV) chloride
(0.53 mL, 4.8 mmol) was added to
a stirred argon
degassed slurry of zinc dust (0.63 g, 9.6 mmol) in THF
(6 mL) in a dropwise fashion through a septum. After
complete addition, the appropriate aldehyde or ketone
(4.0 mmol) was added in one portion. The resulting
metallic slurry was heated in a microwave oven at 110ꢁC
for 10 min using effectively 10 W energy waves. The
15. Procedures for the synthesis of 15: To a solution of 10
(0.69 g, 1 mmol) and acetyl chloride (2 mL) in dichloro-
methane (15 mL) was added boron tribromide (1.0 M
solution in dichloromethane, 4.4 mL, 4.4 mmol). The
resulting dark-colored solution was stirred under nitrogen