1-Bromo-2-(diphenylphosphinoyl)ethyne and 1-bromo-2-(p-tolylsulfinyl)ethyne: versatile reagents eventually leading to benzocyclotrimers

Article abstract of DOI:10.1016/j.tetlet.2009.02.064

The title compounds form Diels-Alder cycloadducts with a number of dienes, which can be transformed into vic-bromo(trimethylstannyl)olefins, ultimate precursors for the synthesis of benzocyclotrimers via copper-mediated cyclotrimerization. The overall res

Full text of DOI:10.1016/j.tetlet.2009.02.064

Tetrahedron Letters 50 (2009) 1973–1976
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1-Bromo-2-(diphenylphosphinoyl)ethyne and 1-bromo-2-(p-tolylsulfinyl)
ethyne: versatile reagents eventually leading to benzocyclotrimers
Pierluigi Padovan a, Stefano Tartaggia a, Silvia Lorenzon a, Enrico Rosso a, Cristiano Zonta b,
Ottorino De Lucchi a, Fabrizio Fabris a,
*
a Dipartimento di Chimica, Università Ca’ Foscari di Venezia, Dorsoduro 2137, I-30123 Venezia, Italy
b Dipartimento di Scienze Chimiche, Università degli Studi di Padova, via Marzolo 1, I-35131 Padova, Italy
a r t i c l e i n f o
a b s t r a c t
Article history:
The title compounds form Diels–Alder cycloadducts with a number of dienes, which can be transformed
into vic-bromo(trimethylstannyl)olefins, ultimate precursors for the synthesis of benzocyclotrimers via
copper-mediated cyclotrimerization. The overall result is a formal condensation of three diatomic car-
bons with three dienes.
Received 13 January 2009
Revised 6 February 2009
Accepted 10 February 2009
Available online 14 February 2009
Ó 2009 Elsevier Ltd. All rights reserved.
Keywords:
Dienophile
Alkyne
Sulfoxide
Phosphine oxide
Cyclotrimerization
Synthetic equivalent
Benzocyclotrimers are useful scaffolds in supramolecular appli-
cations,1 such as complexation of fullerene,2 chiral recognition of
ammonium salts3 and gas hosting in molecular capsule.4 Further-
more, one of these cup-shaped compounds is the crucial precursor
for the synthesis of the smallest, non planar fragment of fullerene,
that is, sumanene.5 These and further applications call for general
and effective synthetic methodologies. In principle, the Diels–Alder
cycloaddition is the most valuable reaction for the synthesis of
suitable substrates for the cyclotrimerization provided that the
functional groups needed to activate the dienophile are convertible
into halogen (bromine) and metal (trimethyltin) moieties which
are needed to promote cyclotrimerization.1–3,5–7 In fact, copper(I)
2-thiophenecarboxylate (CuTC)-mediated cyclotrimerization of
vic-bromo(trimethyltin)olefins is still the most reliable method to
prepare benzocyclotrimers with a wide range of shapes and func-
tional groups.6,8 In an alternative strategy, we have proved that
these two functionalities can be introduced in the diene rather
than in the dienophile (Scheme 1).8,9
H
H
Y
X
X
Y
Ref. 8,9
Y
X
this work
X = Br
Y = SnMe3 or precursors (see text)
Scheme 1. Possible strategies for the synthesis of precursors of benzocyclotrimers.
sulfinyl)ethyne can be regarded as synthetic equivalents of 1-bro-
mo-2-(trimethyltin)ethyne.
The synthesis of 1-bromo-2-(p-tolylsulfinyl)ethyne 1 turned out
to be low yielding and troublesome,14 such as the cycloaddition
reaction was tested with 1,3-cyclopentadiene only providing the
expected cycloadducts in good yield as a separable 1:1 mixture
of diastereomers.15 The latter underwent facile substitution at sul-
fur with phenylmagnesiumbromide. The resulting organomagne-
sium derivative was treated with trimethyltinchloride to afford
2-bromo-3-(trimethyltin)bicyclo[2.2.1]hepta-2,5-diene 37b,16 in
good yields (Scheme 2).
In order to overcome the poor stability of 1, 1-bromo-2-(diphe-
nylphosphinoyl)ethyne was synthesized. Commercially available
trimethylsilylethyne or sodium acetylide was converted into inter-
mediate diphenylphosphinoylethyne (DPE) in good yields.17 The
Both sulfoxide and phosphine oxide groups can efficiently acti-
vate triple bonds for Diels–Alder reactions.10,11 In addition, when
treated with organometallic reagents they can act as leaving
groups in olefins bearing vicinal halogens.12,13 For these reasons,
1-bromo-2-(diphenylphosphinoyl)ethyne and 1-bromo-2-(p-tolyl-
* Corresponding author. Tel.: +39 41 2348908; fax: +39 41 2348517.
E-mail address: fabrisfa@unive.it (F. Fabris).
0040-4039/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tetlet.2009.02.064

1974
P. Padovan et al. / Tetrahedron Letters 50 (2009) 1973–1976
O
Tol
NOE
Br
*
12 Kbar
rt, 48 h
Br
S
Cp
*
POPh2
NOE
Br
SOTol
+
+
*
DCM, 40 ºC
(83% yield)
DCM
SOTol
Br
POPh2
7
Br
1
2a
2b
18
17
(89% yield)
1:1 d.r.
1. PhMgBr
2. Me3SnCl
Scheme 4. High-pressure Diels–Alder reaction of (ꢀ)-nopadiene with 7.
SnMe3
Br
cyclotrimers
THF, r.t
3
(90% yield)
MeMgCl
POPh2
THF, r.t.
Br
Scheme 2. Synthesis of norbornadiene benzocyclotrimers, via cycloaddition of
bromo sulfinyl alkyne 1 and sulfinyl replacement.
- MePOPh2
10
18
Me3SnCl
THF
SnMe3
MgCl
Br
Br
POPh2
Br
3
NBS,
M
H
POPh2
H
(40% yield)
AgNO3 (cat.)
Ref. 17
- MgBrCl
acetone
by-products
19
4: M = SiMe3
5: M = Na
6
7
(76-80% yields)
(94% yield)
Scheme 5. Possible paths of organometallic intermediate generated by 10.
Scheme 3. Synthesis of dienophile 7.
c
c
c
Table 1
Cycloaddition of 7 with 1,3-dienes
c
c
c
Entry
Diene
Cycloadduct
Yielda (%)
27b
POPh2
O2
S
1
Scheme 6. Alternative disconnections for benzocyclotrimers: tribenzyne cycload-
dition (left), versus cyclo-condensation of diatomic carbon (right).
Br
8
POPh2
2
3
48b
80
Br
9
bromination of DPE was achieved with N-bromosuccinimide in the
presence of catalytic amounts of silver(I) nitrate,18 to afford 7 in
good yield and reasonable purity after a simple filtration over basic
alumina (Scheme 3).19
POPh2
Br
10
The cycloaddition of 7 was tested with a number of dienes un-
der standard conditions at 120 °C, affording the expected products
in variable yields (Table 1).20 Nevertheless in the case of cyclo-
pentadiene, when milder conditions (80 °C) were applied for a pro-
longed time (24 h), a nearly quantitative amount of cycloadduct
was obtained.
4
53
POPh2
Br
11
O
O
POPh2
Br
5
6
27
Other 1,3-dienes (1,3,5,7-cyclooctatetraene,
a-phellandrene,
12
naphthalene, 1H-pyrrol-N-(t-butyl)carbamate, 1-tosyl-1H-pyrrole
and nopadiene) failed to afford the expected cycloadducts, because
of concomitant decomposition. In order to avoid the isomerization,
nopadiene 1721 was reacted with the dienophile at rt under high
pressure conditions (12 kbar)22 for 48 hours, to obtain cycloadduct
18 in very good yield as a single stereo- and regio-isomer, as dem-
onstrated by NOESY experiments (Scheme 4).23
The cycloadduct 10 was treated with various Grignard re-
agents24 in THF, followed by quenching with trimethyltinchloride:
when methyl magnesiumchloride was used the desired precursor 3
was obtained, although in modest yield (Scheme 5).
The poor yield can be imputed to the long reaction time re-
quired for the complete consumption of the starting phosphine
oxide: during this time the resulting vic-bromo(chloromagne-
sium)olefin can decompose with elimination of the dihalomagne-
sium salt, leading to the formation of the very reactive strained
alkyne 19.25 Furthermore, when the reaction was carried out in
the presence of a catalytic amount of nickel(II) dichloro[1,2-
bis(diphenylphosphino)ethane], a small amount of syn- and anti-
cyclotrimers was observed in the reaction mixture. Under these
22c
POPh2
Br
13
O
O
O
O
7
8
94
34
POPh2
Br
14
POPh2
Br
15
9
72
POPh2
Br
16
a
Isolated yields.
b
c
Aromatization occurred.
Aromatization occurred via retro Diels–Alder.

P. Padovan et al. / Tetrahedron Letters 50 (2009) 1973–1976
1975
J = 8.2 Hz), 6.50 (1H, dd, J = 3.2 and 4.7 Hz), 6.01 (1H, dd, J = 3.2 and 4.7 Hz),
3.82 (1H, br s), 3.71 (1H, br s), 2.41 (3H, s), 2.34 (1H, dt, J = 6.7 and 1.5 Hz), 2.07
(1H, dd, J = 6.7 and 1.7 Hz); 13C NMR (CDCl3, 75 MHz) d (ppm): 153.0, 142.4,
141.0, 140.9, 137.8, 136.3, 129.7, 124.0, 70.8, 60.1, 48.3; MS (70 eV): m/z: 260–
262 (M+ꢀSO, 25), 229 (51), 181 (57), 166 (56), 89 (89), 77 (100%).
conditions nickel can either mediate the coupling between organo-
magnesium species with halides26 or stabilize the strained alkyne
by complexation.27
In conclusion, in this Letter we describe the use of two different
dienophiles for the synthesis of cycloadducts that can be converted
to precursors of functionalized cyclotrimers. The overall path is
such that the dienophile can be regarded as a synthetic equivalent
of diatomic carbon, or it can resemble a cycloaddition of cyclohex-
atriene with three dienes (Scheme 6).
16. Cossu, S.; Cimenti, C.; Peluso, P.; Paulon, A.; De Lucchi, O. Angew. Chem., Int. Ed.
2001, 40, 4086–4089. Noteworthy, compound
3 and the related syn-
cyclotrimer are key intermediates for the synthesis of sumanene: Ref. 5.
17. Pellizzaro, L.; Tatibouët, A.; Fabris, F.; Rollin, P.; De Lucchi, O. Tetrahedron Lett.
2009, 50, 101–103.
18. Bellina, F.; Carpita, A.; Mannocci, L.; Rossi, R. Eur. J. Org. Chem. 2004, 2610–
2619; Zhang, C.; Ballay, C. J., II; Trudell, M. L. J. Chem. Soc., Perkin Trans. 1 1999,
675–676; Leroy, J. Org. Synth. 1998, Coll. Vol. 9, 129–133.
19. An analytical sample of 1-bromo-2-(diphenylphosphinoyl)ethyne (7) was
obtained by FC on silica-gel (eluant AcOEt/hexanes 6:4): mp 67 °C. 1H NMR
(CDCl3, 200 MHz, TMS) d 7.91–7.75 (4H, Ar, m), 7.36–7.42 (6H, Ar, m); 13C NMR
(CDCl3, 50 MHz, TMS) d 132.2 (Ar, JPCipso = 122.8 Hz), 132.4 (Ar, JCPpara = 3.0 Hz),
130.9 (Ar, JCPmeta = 11.4 Hz), 128.7 (Ar, JCPortho = 13.7 Hz), 76.4 (C„C,
JCP = 161.0 Hz), 69.2 (C„C, JCP = 26.2 Hz); 31P NMR (CDCl3, 80 MHz, H3PO4) d
Acknowledgement
This work was co-funded by MIUR (Rome) within the national
PRIN framework.
9.17; IR (KBr)
(100), 178 (24), 77 (23%).
20. General cycloaddition procedure. In a screw-capped Pyrex test tube, a solution of
m 3058, 2141, 1200. GC–MS (EI, 70 eV) m/z 306–304 (8), 225
References and notes
7
(915 mg, 3.0 mmol), diene (1 equiv for entry 4; 1.2 equiv for entry 7;
1. Rieth, S.; Yan, Z.; Xia, S.; Gardlik, M.; Chow, A.; Fraenkel, G.; Hadad, C. M.;
1.5 equiv for entries 5, 6, 9; 2.0 equiv for entries 2, 3, 8; 4.0 equiv for entry 1)
and hydroquinone (5 mg) in toluene (1 mL) was purged with argon, sealed and
heated at 120 °C for 18 h. The mixture was purified by flash-chromatography
(eluant 1:1 AcOEt/hexanes). 1-Bromo-2-(diphenylphosphinoyl)cyclohexa-1,4-
diene (8). Waxy solid. 1H NMR (200 MHz, CDCl3, TMS) d (ppm): 7.85–7.63 (4H,
m), 7.60–7.30 (6 H, m), 5.74–5.47 (2H, m), 3.39–3.23 (2H, m), 2.82–2.66 (2H,
m); 31P NMR (81 MHz, CHCl3, H3PO4) d (ppm): 29.7; 13C NMR (50 MHz, CHCl3,
´
Badjic, J. D. J. Org. Chem. 2008, 73, 5100–5109; Yan, Z.; McCracken, T.; Xia, S.;
Maslak, V.; Gallucci, J.; Hadad, C. M.; Badjic´, J. D. J. Org. Chem. 2008, 73, 355–
363; Yan, Z.; Xia, S.; Gardlik, M.; Seo, W.; Maslak, V.; Gallucci, J.; Hadad, C. M.;
Badjic´, J. D. Org. Lett. 2007, 9, 2301–2304; Maslak, V.; Yan, Z.; Xia, S.; Gallucci, J.;
Hadad, C. M.; Badjic´, J. D. J. Am. Chem. Soc. 2006, 128, 5887–5894.
2. Zonta, C.; Cossu, S.; De Lucchi, O. Eur. J. Org. Chem. 2000, 1965–1971.
3. Fabris, F.; Pellizzaro, L.; Zonta, C.; De Lucchi, O. Eur. J. Org. Chem. 2007, 283–291.
4. Scarso, A.; Pellizzaro, L.; De Lucchi, O.; Linden, A.; Fabris, F. Angew. Chem., Int.
Ed. 2007, 46, 4972–4975.
TMS)
d (ppm): 135.9 (d, J = 10.6 Hz), 134.5 (d, J = 24.8 Hz), 133.9 (d,
J = 104.0 Hz), 133.4 (d, J = 2.4 Hz), 131.9 (d, J = 2.8 Hz), 131.7 (d, J = 10.0 Hz),
128.6 (d, J = 12.4 Hz), 123.0 (d, J = 8.8 Hz), 122.7 (d, J = 1.3 Hz), 39.6 (d,
5. Higashibayashi, S.; Sakurai, H. J. Am. Chem. Soc. 2008, 130, 8592–8593; Amaya,
T.; Sakane, H.; Hirao, T. Angew. Chem., Int. Ed. 2007, 46, 8376–8379;
Higashibayashi, S.; Sakurai, H. Chem. Lett. 2007, 36, 18–19.
J = 7.7 Hz), 33.0 (d, J = 10.2 Hz); IR (KBr)
m
1187 (PO) cmꢀ1; m/z (EI, 70 eV):
358–360 (M+, 20), 359–357 (M+ꢀH, 55), 357–355 (80), 277 (80), 199 (90), 152
(97), 77 (100%). 1-Bromo-2-(diphenylphosphinoyl)-4,5-dimethylcyclohexa-
1,4-diene (9). Waxy solid. 1H NMR (200 MHz, CDCl3, TMS) d (ppm): 7.84–
7.67 (4H, m), 7.60–7.38 (6 H, m), 3.28–3.13 (2H, m), 2.81–2.64 (2H, m), 1.60
(3H, s), 1.52 (3H, s); 31P NMR (81 MHz, CHCl3, H3PO4) d (ppm): 29.1; 13C NMR
(50 MHz, CHCl3, TMS) d (ppm): 133.2 (d, JC–P = 20.5 Hz), 131.8 (d, JC–P = 2.8 Hz),
131.7 (d, JC–P = 10.0 Hz), 131.0 (d, JC–P = 9.6 Hz), 129.9 (d, JC–P = 93.6 Hz), 128.5
6. Borsato, G.; Brussolo, S.; Crisma, M.; De Lucchi, O.; Lucchini, V.; Zambon, A.
Synlett 2005, 1125–1128; Borsato, G.; De Lucchi, O.; Fabris, F.; Groppo, L.;
Lucchini, V.; Zambon, A. J. Org. Chem. 2002, 67, 7894–7897; Borsato, G.; De
Lucchi, O.; Fabris, F.; Lucchini, V.; Pasqualotti, M.; Zambon, A. Tetrahedron Lett.
2003, 44, 561–563; Fabris, F.; Bellotto, L.; De Lucchi, O. Tetrahedron Lett. 2003,
44, 1211–1213; Dastan, A.; Fabris, F.; De Lucchi, O.; Güney, M.; Balci, M. Helv.
Chim. Acta 2003, 86, 3411–3416; De Lucchi, O.; Dasßtan, A.; Altundaßs, A.; Fabris,
F.; Balcı, M. Helv. Chim. Acta 2004, 87, 2364–2368.
7. (a) Zonta, C.; Cossu, S.; Peluso, P.; De Lucchi, O. Tetrahedron Lett. 1999, 40,
8185–8188; (b) Durr, R.; Cossu, S.; Lucchini, V.; De Lucchi, O. Angew. Chem., Int.
Ed. 1997, 36, 2805–2807.
8. Zonta, C.; Fabris, F.; De Lucchi, O. Org. Lett. 2005, 7, 1003–1006.
9. Dalkılıç, E.; Güney, M.; Dasßtan, A.; Saracoglu, N.; De Lucchi, O.; Fabris, F.,
Tetrahedron Lett. 2009, doi:10.1016/j.tetlet.2009.02.070.
(d, JC–P = 12.4 Hz), 122.5 (d, JC–P = 6.4 Hz), 122.4 (d, JC–P = 0.8 Hz), 46.0 (d, JC–P
=
8.0 Hz), 39.0 (d, JC–P = 9.2 Hz), 17.7, 17.5; IR (KBr)
m
1199 (P@O) cmꢀ1; m/z (EI,
70 eV): 388–386 (M+, 25), 385–388 (M+ꢀH, 85), 305–307 (80), 227 (80), 201
(100), 77 (97%). 2-Bromo-3-(diphenylphosphinoyl)bicyclo[2.2.1]hepta-2,5-
diene (10). Oil. 1H NMR (200 MHz, CDCl3, TMS) d (ppm): 7.76–7.37(10 H,
series of m), 6.86 (1H, dd, J = 4.9 and 3.0 Hz), 6.76 (1H, dd, J = 4.9 and 3.0 Hz),
3.95 (1H, br s), 3.75 (1H, br s), 2.42 (1H, dt, J = 6.7 and 1.8 Hz), 2.07(1H, br d,
J = 6.7 Hz); 31P NMR (81 MHz, CHCl3, H3PO4) d (ppm): 24.1; 13C NMR (50 MHz,
CHCl3, TMS) d (ppm): 151.1 (d, JC–P = 4.4 Hz), 142.9 (d, JC–P = 0.8 Hz), 141.5 (d,
10. CC-SOAr: Lee, A. W. M.; Chan, W. H.; Wong, M. S. J. Chem. Soc., Chem. Commun.
1989, 1585–1586; Maignan, C.; Belkasmioui, F. Tetrahedron Lett. 1988, 29,
2823–2824.
JC–P = 112.8 Hz), 140.0 (d, JC–P = 2.0 Hz), 132.4 (d, JC–P = 38.9 Hz), 132.0 (d, JC–P
=
2.8 Hz), 131.9 (d, JC–P = 2.8 Hz), 131.6 (d, JC–P = 10.4 Hz, two overlapping C),
130.2 (d, JC–P = 38.5 Hz), 128.5 (d, JC–P = 12.4 Hz), 128.4 (d, JC–P = 12.4 Hz), 72.3
11. CC-POAr2: Huang, Y. D.; Yu, H. T.; Meng, J. B.; Matsuura, T.; Wang, Y. M. J. Mol.
Struct. 2002, 610, 247–252; Huang, Y. D.; Meng, J. B.; Yu, H. T.; Matsuura, T.;
Wang, Y. M. Mol. Struct. 2002, 604, 119–124; Rheingold, A. L.; Liable-Sands, L.
M.; Trofimenko, S. Angew. Chem., Int. Ed. 2000, 39, 3321–3324; Arnaud-Neu, F.;
Browne, J. K.; Byrne, D.; Marrs, D. J.; McKervey, M. A.; O’Hagan, P.; Schwing-
Weill, M. J.; Walker, A. Chem. Eur. J. 1999, 1, 175–186; Fu, T. Y.; Liu, Z.;
Olovsson, G.; Scheffer, J. R.; Trotter, J. Acta Crystallogr., Sect. B 1997, 53, 293–
299; Palacios, F.; Ochoa de Retana, A. M.; Pagalday, J. Heterocycles 1994, 38, 95–
102.
12. Capozzi, M. A. M.; Cardellicchio, C.; Naso, F. Eur. J. Org. Chem. 2004, 1855–1863.
13. Cardellicchio, C.; Fiandanese, V.; Naso, F.; Pacifico, S.; Koprowski, M.;
Pietrusiewicz, K. M. Tetrahedron Lett. 1994, 35, 6343–6346; Cardellicchio, C.;
Fiandanese, V.; Naso, F.; Pietrusiewicz, K. M.; Wisniewski, W. Tetrahedron Lett.
1993, 34, 3135–3138.
14. Obtained according to the reported methodology for 1-bromo-2-
(phenylsulfinyl)ethyne: Hori, I.; Oishi, T. Tetrahedron Lett. 1979, 42, 4087-
4090. An analytical sample of 1-bromo-2-(p-tolylsulfinyl)ethyne (1) was
obtained by FC on silica-gel (eluant Et2O/hexanes 3:7): pale yellow oil stable
for several months in CDCl3 solution in refrigerator, which rapidly polymerizes
when concentrated. 1H NMR (CDCl3, 200 MHz, TMS) d 7.68 (2H, d, J = 7.0 Hz);
7.36 (2H, d, J = 7.0 Hz); 2.44 (3H, s); 13C NMR (CDCl3, 50 MHz, TMS) d 142.9,
(d, JC–P = 4.4 Hz), 63.0 (d, JC–P = 9.3 Hz), 55.1 (d, JC–P = 8.8 Hz); IR (film)
m 1182
(P@O) cmꢀ1; m/z (EI, 70 eV): 370–372 (M+, 3), 369–371 (M+ꢀH, 4), 355–307
(8), 291 (100), 201 (50), 77 (70%). 2-Bromo-3-(diphenylphosphinoyl)-7-
isopropylidenebicyclo[2.2.1]hepta-2,5-diene
(11).
Colourless
crystals
mp = 102–103 °C (dec); 1H NMR (200 MHz, CDCl3, TMS) d (ppm): 7.27–7.32
(10H, series of m), 6.89 (1H, ddd, J = 4.3, 3.0 and 1.2 Hz), 6.79 (1H, dd, J = 4.3
and 3.0 Hz), 4.30–4.21 (1H, m), 4.18–4.11 (1H, m), 1.45 (3H, s), 1.35 (3H, s); 31P
NMR (81 MHz, CHCl3, H3PO4) d (ppm): 24.1; 13C NMR (50 MHz, CHCl3, TMS) d
(ppm): 160.2 (d, JC–P = 5.2 Hz), 149.5 (d, JC–P = 4.8 Hz), 142.3 (d, JC–P = 1.2 Hz),
141.3 (d, JC–P = 110.8 Hz), 140.0 (d, JC–P = 2.0 Hz), 132.3 (d, JC–P = 9.6 Hz), 131.91
(d, JC–P = 2.8 Hz), 131.89 (d, JC–P = 2.8 Hz), 131.6 (d, JC–P = 10.4 Hz), 131.4 (d,
JC–P = 10.4 Hz), 130.2 (d, JC–P = 9.2 Hz), 128.42 (d, JC–P = 12.4 Hz), 128.38 (d,
JC–P = 12.8 Hz), 99.2, 62.5 (d, JC–P = 7.6 Hz), 55.3 (d, JC–P = 9.2 Hz), 18.4, 18.1; IR
(KBr.)
m
1198 (P@O) cmꢀ1; m/z (EI, 70 eV): 410–412 (M+, 7), 409–411 (M+ꢀH,
15), 201 (25), 141 (75), 57 (100%). 2-Bromo-3-(diphenylphosphinoyl)-7-
oxabicyclo[2.2.1]hepta-2,5-diene (12). Colourless crystals mp = 125–127 °C
(dec); 1H NMR (200 MHz, CDCl3, TMS) d (ppm): 7.78–7.39 (10 H, series of
m), 7.16 (1H, dd, J = 5.4 and 1.8 Hz), 7.06 (1H, dd, J = 5.4 and 1.8 Hz), 5.69 (1H,
br q, J = 1.5 Hz), 5.37–5.34 (1H, m); 31P NMR (81 MHz, CHCl3, H3PO4) d (ppm):
21.9; 13C NMR (50 MHz, CHCl3, TMS) d (ppm): 151.6 (d, JC–P = 4.0 Hz), 144.6 (d,
JC–P = 0.8 Hz), 142.8 (d, JC–P = 113.2 Hz), 140.5 (d, JC–P = 1.6 Hz), 132.4 (d, JC–P
=
140.2, 130.2, 125.1, 78.2, 66.8, 21.4; IR (film)
809, 537; GC–MS (EI, 70 eV): m/z 194–196 (13), 155 (54), 139 (100), 91 (31), 65
(40).
m 3056, 2925, 2130, 1089, 1059,
3.2 Hz, two overlapping C), 131.7 (d, JC–P = 10.4 Hz), 131.5 (d, JC–P = 10.4 Hz),
130.7 (d, JC–P = 110.8 Hz), 130.2 (d, JC–P = 110.8 Hz), 128.8 (d, JC–P = 12.8 Hz),
128.7 (d, JC–P = 12.8 Hz), 90.5 (d, JC–P = 9.2 Hz), 87.2 (d, JC–P = 11.6 Hz); IR (KBr)
m
15. Diastereomers of 2-bromo-3-(phenylsulfinyl)-bicyclo[2.2.1]hepta-2,5-diene 2a
and 2b were separated by flash-chromatography (eluant 6:4 diethylether/
hexanes). First eluant: colourless oil (44% yield). 1H NMR (CDCl3, 300 MHz) d
(ppm): 7.55 (2H, d, J = 8.3 Hz), 7.34 (2H, d, J = 8.3 Hz), 6.92 (1H, dd, J = 5.0 and
3.0 Hz), 6.84 (1H, dd, J = 5.0 and 3.0 Hz), 3.70 (1H, br s), 3.65 (1H, br s), 2.44
(3H, s), 2.04 (1H, dt, J = 6.6 and 1.8 Hz), 1.99 (1H, dd, J = 6.6 and 1.4 Hz); 13C
NMR (CDCl3, 75 MHz) d (ppm): 153.0, 143.4, 142.9, 141.09, 140.1, 129.9, 129.7,
124.0, 72.0, 60.1, 50.1, 21.4; MS (70 eV): m/z 260–262 (M+ꢀSO, 24), 229 (50),
181 (56), 166 (55), 89 (91), 77 (100%). Second eluate: colourless oil, (39% yield).
1186 (P@O) cmꢀ1; m/z (EI, 70 eV): 355–357 (M+ꢀO, 10), 280–282 (15), 133
(60), 95 (65), 76 (100%). 2-Bromo-3-(diphenylphosphinoyl)bicyclo[2.2.2]octa-
2,5-diene (13). Colourless crystals mp = 130–4 °C (dec); 1H NMR (200 MHz,
CDCl3, TMS) d (ppm): 7.78–7.30 (10 H, series of m), 6.40–6.30 (2H, m), 4.16–
4.00 (1H, m), 3.96–3.82 (1H, m), 1.50–1.20 (4H, m); 31P NMR (81 MHz, CHCl3,
H3PO4) d (ppm): 26.4; 13C NMR (50 MHz, CHCl3, TMS) d (ppm): 138.8 (d, JC–P
2.8 Hz), 135.5 (d, JC–P = 106.0 Hz), 133.8 (d, JC–P = 3.6 Hz), 132.8 (d, JC–P
=
=
2.0 Hz), 131.8 (d, JC–P = 108.0 Hz), 131.7 (d, JC–P = 3.2 Hz), 131.6 (d,
JC–P = 2.8 Hz), 131.5 (d, JC–P = 107.2 Hz), 131.5 (d, JC–P = 10.4 Hz), 131.4 (d,
1H NMR (CDCl3, 300 MHz)
d (ppm): 7.35 (2H, d, J = 8.2 Hz), 7.28 (2H, d,

1976
P. Padovan et al. / Tetrahedron Letters 50 (2009) 1973–1976
JC–P = 10.4 Hz), 128.3 (d, JC–P = 12.8 Hz, two overlapping C), 51.2 (d, JC–P
=
JC–P = 7.2 Hz), 55.0 (d, JC–P = 8.8 Hz); IR (KBr) m
1184 (P@O) cmꢀ1; m/z (EI,
7.2 Hz), 41.7 (d, JC–P = 8.4 Hz), 24.9 (d, JC–P = 1.6 Hz), 24.6 (d, JC–P = 2.0 Hz); IR
70 eV): 484–482 (M+, 1), 403 (M+ꢀBr, 7), 201 (30), 178 (100%).
21. Paquette, L. A.; Gugelcuck, M.; McLaughlin, M. L. J. Org. Chem. 1987, 52, 4732–
4740.
(KBr)
m
1190 (P@O) cmꢀ1; m/z (EI, 70 eV): 358–356 (M+ꢀC2H4, 55), 357–355
(70), 277 (60), 199 (85), 183 (70), 152 (100), 77 (97%). 8-Bromo-9-
(diphenylphosphinoyl)-4,4-dimethyl-3,5-dioxatricyclo[5.2.2.02,6]undeca-8,10-
diene (14). Colourless crystals mp = 153–155 °C (dec.) (Et2O). 1H NMR
(200 MHz, CDCl3, TMS) d (ppm): 7.77–7.40 (10 H, series of m), 6.43 (1H,
pseudo-t, J = 6.3 Hz), 6.33 (1H, pseudo-t, J = 6.3 Hz), 4.51 (1H, dd, J = 6.9 and
3.5 Hz), 4.31 (1H, dd, J = 6.9 and 3.5 Hz), 4.20–4.07 (2H, m), 1.29 (3H, s), 1.25
(3H, s); 31P NMR (81 MHz, CHCl3, H3PO4) d (ppm): 26.3; 13C NMR (50 MHz,
CHCl3, TMS) d (ppm): 139.2 (d, JC–P = 3.2 Hz), 134.6 (d, JC–P = 104.2 Hz), 131.3
(d, JC–P = 108.4 Hz), 131.2 (d, JC–P = 108.0 Hz), 132.19 (d, JC–P = 2.9 Hz), 132.17
(d, JC–P = 2.8 Hz), 131.7 (d, JC–P = 11.5 Hz), 131.5 (d, JC–P = 11.1 Hz), 131.4 (d,
JC–P = 3.4 Hz), 131.0 (d, JC–P = 1.9 Hz), 128.8 (d, JC–P = 12.8 Hz), 128.7 (d,
JC–P = 12.5 Hz), 113.6, 78.0 (d, JC–P = 3.0 Hz), 77.5 (d, JC–P = 2.9 Hz), 56.6 (d,
22. Minuti, L.; Taticchi, A.; Marrocchi, A.; Broggi, A. Tetrahedron: Asymmetry 2004,
15, 1187–2119.
23. A solution of 7 (1.04 g, 3.4 mmol) and nopadiene (666 mg, 4.5 mmol) in DCM
was placed in a 3 mL screw-capped Teflon capsule that was submitted to 12
Kbar pressure for 48 hours at r.t. The volatile materials were removed, and the
residue was recrystallized from AcOEt to afford 1.39 g (89% yield) of 5-bromo-
6-(diphenylphosphinoyl)-9,9-dimethyl-1,2,3,4,4a,7-hexahydro-1,3-
methanonaphthalene (18) as colourless crystals, mp = 184–185 °C. ½a D22
ꢀ12 (c
ꢁ
1.4, CHCl3); 1H NMR (300 MHz, CDCl3, TMS) d (ppm): 7.68–7.76 (4H, series of
m), 7.41–7.56 (6H, series of m), 5.31 (1H, m), 3.75 (1H, m), 2.48–2.82 (4H,
series of m), 2.08–2.38 (3H, series of m), 1.27 (3H, s), 0.97 (3H, s), 0.90 (1H, d,
J = 8.9 Hz); 31P NMR (122 MHz, CDCl3, H3PO4) d (ppm): 30.6; 13C NMR (75 MHz,
CDCl3, TMS) d (ppm): 143.7 (d, J = 1.5 Hz), 143.3, 132.6 (d, J = 106.2 Hz), 132.3
(d, J = 105.0 Hz), 132.1 (d, J = 3.4 Hz), 132.0 (d, J = 3.4 Hz), 131.7 (d, J = 9.7 Hz),
131.6 (d, J = 9.9 Hz), 128.6 (d, J = 101.2 Hz), 128.5 (d, J = 12.3 Hz), 128.4 (d,
J = 12.3 Hz), 115.4 (d, J = 9.0 Hz), 51.1, 42.3, 40.2 (d, J = 7.9 Hz), 39.5, 35.7, 34.0,
JC–P = 7.1 Hz), 46.6 (d, JC–P = 8.0 Hz), 25.7, 25.6; IR (KBr) m
1189 (P@O) cmꢀ1; m/z
(EI, 70 eV): 358–356 (M+ꢀC5H8O2, 27), 357–355 (M+ꢀC5H9O2, 70), 277 (30),
199 (60), 152 (70), 77 (100%). 8-Bromo-9-(diphenylphosphinoyl)tetracyclo
[4.3.0.2,403,7]non-8-ene (15). Colourless crystals mp = 130–3 °C; 1H NMR
(200 MHz, CDCl3, TMS) d (ppm): 7.80–7.62 (4H, m), 7.60–7.37(6 H, m), 2.97–
2.88 (2H, m), 2.37 (1H, br s), 1.84–1.76 (1H, m), 1.70–1.62 (1H, m), 1.57 (2H, br
s), 1.49–1.41 (1H, m); 31P NMR (81 MHz, CHCl3, H3PO4) d (ppm): 23.4; 13C NMR
33.8 (d, J = 10.6 Hz), 27.0, 23.2; IR (KBr)
m .
1187 (P@O) cmꢀ1
24. PhMgBr furnished no products, presumably because of steric hindrance.
Me2 Mg/MgI2 in THF furnished only 10–15% yields of 3.
(50 MHz, CHCl3, TMS)
d
(ppm): 140.9 (d, JC–P = 2.4 Hz), 136.7 (d, JC–P
=
=
110.0 Hz), 134.0 (d, JC–P = 65.8 Hz), 132.0 (d, JC–P = 75.5 Hz), 131.8 (d, JC–P
25. Laird, D. W.; Gilbert, J. C. J. Am. Chem. Soc. 2001, 123, 6704–6705; Kitamura, T.;
Kotani, M.; Yokoyama, T.; Fujiwara, Y. J. Org. Chem. 1999, 64, 680–681;
Kenndoff, J.; Polborn, K.; Szeimies, G. J. Am. Chem. Soc. 1990, 112, 6117–6118;
Harold, H.; Shamouil, S.; Yoshikazu, T. J. Org. Chem. 1981, 46, 4427–4432;
Brewer, J. P. N.; Heaney, H.; Marples, B. A. Chem. Commun. (London) 1967, 27–
28.
26. Busacca, C. A.; Eriksson, M. C.; Fiaschi, R. Tetrahedron Lett. 1999, 40, 3101–3104;
Kottirsch, G.; Szeimies, G. Chem. Ber. 1990, 123, 1495–1505; Walker, J. A.;
Bitler, S. A.; Wudl, F. J. Org. Chem. 1984, 49, 4733–4734.
27. Bennet, M. A. Pure Appl. Chem. 1989, 61, 1700–1965; Pericàs, M. A.; Riera, A.;
Rossell, O.; Serratosa, F.; Seco, M. J. Chem. Soc., Chem. Commun. 1988, 942–943;
Iyoda, M.; Kuwatani, Y.; Yamauki, T.; Oda, M. J. Chem. Soc., Chem. Commun.
1988, 65–66.
3.2 Hz, two overlapping C), 131.6 (d, JC–P = 10.4 Hz), 131.5 (d, JC–P = 10.4 Hz),
131.2 (d, JC–P = 62.6 Hz), 128.4 (d, JC–P = 13.6 Hz, two overlapping C), 61.0 (d,
JC–P = 9.6 Hz), 56.8 (d, JC–P = 4.8 Hz), 53.8 (d, JC–P = 8.8 Hz), 32.4, 26.7, 23.8 (d,
JC–P = 0.8 Hz), 23.4 (d, JC–P = 2.8 Hz); IR (KBr)
m
1194 (P@O) cmꢀ1; m/z (EI,
70 eV): 398–396 (M+, 7), (M+ꢀH, 17), 317 (28), 201 (100), 115 (60), 77 (50%).
11-Bromo-12-(diphenylphosphinoyl)-9,10-dihydro-9,10-ethenylantracene (16).
Colourless crystals mp = 130–132 °C (dec); 1H NMR (200 MHz, CDCl3, TMS) d
(ppm): 7.60–7.32 (12H, m), 7.14–6.94 (8 H, m), 5.34–5.25 (2H, m); 31P NMR
(81 MHz, CHCl3, H3PO4) d (ppm): 28.0; 13C NMR (50 MHz, CHCl3, TMS) d (ppm):
146.2 (d, JC–P = 2.8 Hz), 143.2 (d, JC–P = 2.8 Hz), 143.1 (d, JC–P = 2.0 Hz), 138.8 (d,
JC–P = 103.6 Hz), 132.1 (d, JC–P = 2.8 Hz), 131.8 (d, JC–P = 10.4 Hz), 131.1 (d,
JC–P = 108.8 Hz), 128.5 (d, JC–P = 12.4 Hz), 125.7, 125.2, 123.6, 123.4, 64.3 (d,