Benzannulation via sequential metal-promoted higher-order cycloaddition-Ramberg-Baecklund rearrangement

Full text of DOI:10.1021/jo9616419

7644
J . Org. Chem. 1996, 61, 7644-7645
Sch em e 1
Ben za n n u la tion via Sequ en tia l
Meta l-P r om oted High er -Or d er
Cycloa d d ition -Ra m ber g-Ba1ck lu n d
Rea r r a n gem en t
J ames H. Rigby* and Namal C. Warshakoon
Ta ble 1. Cr (0)-P r om oted
Cycloa d d ition -Ra m ber g-Ba1ck lu n d
Department of Chemistry, Wayne State University,
Detroit, Michigan 48202-3489
Received August 26, 1996
Aromatic ring assembly from acyclic precursors (ben-
zannulation) has been the subject of considerable study
in recent years.1 Advances in this field based on Fischer
carbene complexes (the Do¨tz reaction),2 cobalt-mediated
alkyne cyclotrimerization,3 cyclobutenone and cyclobutene-
dione rearrangements,4 vinyl ketene cycloaddition,5 as
well as other cyclization protocols6 permit construction
of a wide range of fused arene ring systems, often of
considerable complexity.
We now disclose a novel benzannulation sequence
based on chromium(0)-promoted [6π + 4π] cycloaddition7
followed by a Ramberg-Ba¨cklund rearrangement8
(Scheme 1). A noteworthy feature of this two-operation
methodology that sets it apart from many related annu-
lation procedures is the simultaneous production of two
rings during the cyclization event. The high level of
convergency that characterizes the overall process is also
significant; for instance, all of the carbon atoms compris-
ing the arene substructures are introduced in a single
step via the thiepin dioxide triene system. Furthermore,
since a wide range of diene partners are known to
a
Typical reaction conditions: (A) hν (U-glass), ClCH2CH2Cl; (ii)
t-BuOK/THF, -105 °C; (iii) N-chlorosuccinimide, THF; (iv) t-
b
BuOK/THF, -105 °C. Overall isolated yield for entire sequence.
c Yields depressed due to product volatility. Reference 14.
d
participate in metal-mediated higher-order cycloaddition,
the methodology offers versatility with regard to potential
target structures. These aspects of the chemistry com-
bine to render the sequence particularly amenable to the
rapid buildup of molecular complexity.
Equation 1 presents a typical benzannulation se-
quence. Irradiation (uranium glass filter) of readily
(1) For a review covering certain aspects of this chemistry, see:
Bamfield, P.; Gordon, P. F. Chem. Soc. Rev. 1984, 13, 441.
(2) Reviews: (a) Do¨tz, K. H. Angew Chem., Int. Ed. Engl. 1984, 23
587. (b) Wulff, W. D. In Advances in Metal-Organic Chemistry;
Liebeskind, L. S., Ed.; J AI Press: Greenwich, CT, 1989; Vol. 1, pp 209-
393. Selected recent developments: (c) Hsung, R. P.; Wulff, W. D.;
Rheingold, A. L. J . Am. Chem. Soc. 1994, 116, 6449. (d) Semmelhack,
M. F.; Ho, S.; Cohen, D.; Steigerwald, M.; Lee, M. C.; Lee, G.; Gilbert,
A. M.; Wulff, W. D.; Ball, R. G. Ibid. 1994, 116, 7108. (e) Chamberlain,
S.; Waters, M. L.; Wulff, W. D. Ibid. 1994, 116, 3113. (f) Gross, M. F.;
Finn, M. G. Ibid. 1994, 116, 10921. (g) Painter, J . E.; Quayle, P.; Patel,
P. Tetrahedron Lett. 1995, 36, 8089. (h) Hsung, R. P.; Xu, Y. -C.; Wulff,
W. D. Ibid. 1995, 36 8159. (i) Do¨tz, K. H.; Pfeiffer, J . J . Chem. Soc.,
Chem. Commun. 1996, 895.
(3) (a) Vollhardt, K. P. C. Angew Chem., Int. Ed. Engl. 1984, 23,
539. (b) Earl, R. A.; Vollhardt, K. P. C. J . Org. Chem. 1984, 49, 4786.
(c) Liebeskind, L. S.; Leeds, J . P.; Baysdon, S. L.; Iyer, S. J . Am. Chem.
Soc. 1984, 106, 6451. (d) J ohnson, E. P.; Vollhardt, K. P. C. Ibid. 1991,
113, 381. (e) Saito, S.; Salter, M. M.; Genorgyan, V.; Tsuboya, N.;
Tando, K.; Yamamoto, Y. J . Am. Chem. Soc. 1996, 118, 3970.
(4) (a) Liebeskind, L. S.; Wang, J . J . Org. Chem. 1993, 58, 3550. (b)
Krysan, D. J .; Gurski, A.; Liebeskind, L. S. J . Am. Chem. Soc. 1992,
114, 1412. (c) Liebeskind, L. S. Tetrahedron 1989, 45, 3053. (d) Foland,
L. D.; Karlsson, J . O.; Perri, S. T.; Schwabe, R.; Xu, S. L.; Patil, S.;
Moore, H. W. J . Am. Chem. Soc. 1989, 111, 975.
(5) (a) Danheiser, R. L.; Brisbois, R. G.; Kowalczyk, J . J .; Miller, R.
F. J . Am. Chem. Soc. 1990, 112, 3093. (b) Danheiser, R. L.; Miller, R.
F.; Brisbois, R. G.; Park, S. Z. J . Org. Chem. 1990, 55, 1959. (c)
Danheiser, R. L.; Sard, H. Ibid. 1980, 45, 4810.
(6) (a) Chen, Y. P.; Chantegrel, B.; Deshayes, C. Heterocycles 1995,
41, 175. (b) Ciufolini, M. A.; Weiss, T. J . Tetrahedron Lett. 1994, 35,
1127. (c) Hauser, F. M.; Rhee, R. P. J . Org. Chem. 1978, 43, 178. (d)
Hauser, F. M.; Caringal, Y. J . Org. Chem. 1990, 55, 555. (e) Kraus, G.
A.; Cho, H.; Crowley, S.; Roth, B.; Sugimoto, H.; Prugh, S. Ibid. 1983,
48, 3439. (f) Tius, M. A.; Ali, S. Ibid. 1982, 47, 3163.
available (η6-thiepin 1,1-dioxide)tricarbonylchromium(0)
(1)9 in the presence of diene 210 provided cycloadduct 311
in 75% yield. Treatment of this tricycle in one pot with
t-BuOK in THF at -105 °C12 followed by trapping of the
intermediate carbanion with N-chlorosuccinimide and
exposure of the resultant mixture to a second equivalent
of t-BuOK afforded the known hexahydroanthracene 4
in quite good yield.13
A noteworthy feature of this benzannulation sequence
is the capability of assembling polycyclic products as
single diastereoisomers. This point is illustrated in eqs
2 and 3 wherein cycloaddition of chiral, nonracemic
(9) Rigby, J . H.; Ateeq, H. S.; Krueger, A. C. Tetrahedron Lett. 1992,
23, 5873.
(7) For reviews, see: (a) Rigby, J . H. Acc. Chem. Res. 1993, 26, 579.
(b) Rigby, J . H. In Advances in Metal-Organic Chemistry; Liebeskind,
L. S., Ed.; J AI Press: Greenwich, CT, 1995; Vol. 4, pp 89-127.
(8) Review: (a) Paquette, L. A. Org. React. 1977, 25, 1. Recent uses
in synthesis: (b) Grumann, A.; Marley, H.; Taylor, R. J . K. Tetrahedron
Lett. 1995, 36, 7767. (c) Doomes, E.; McKnight, A. A. J . Heterocycl.
Chem. 1995, 32, 1467. (d) Alvarez, E.; Diaz, M. T.; Hanxing, L; Martin,
J . D. J . Am. Chem. Soc. 1995, 117, 1437. (e) Trost, B. M.; Shi, Z. Ibid.
1994, 116, 7459. (f) Nicolaou, K. C.; Zuccarello, G.; Riemer, C.; Estevez,
V. A.; Dai, W.-M. Ibid. 1992, 114, 7360.
(10) Block, E.; Aslam, M. Org. Synth. 1987, 65, 90.
(11) This compound exhibited spectral (1H NMR, 13C NMR, IR) and
analytical (combustion analysis and/or HRMS) data consistent with
the assigned structure.
(12) Metalated dihydrothiepin 1,1-dioxides rapidly decompose at
temperatures above -105 °C: Rigby, J . H.; Kreuger, A. C. Synlett 1993,
829.
(13) Thummel, R. P.; Cravey, W. E.; Cantu, D. B. J . Org. Chem.
1980, 45, 1633.
(14) Yasuda, M.; Pac, C.; Sakurai, H. J . Org. Chem. 1981, 46, 788.
S0022-3263(96)01641-6 CCC: $12.00 © 1996 American Chemical Society

Communications
J . Org. Chem., Vol. 61, No. 22, 1996 7645
dienes provided diastereomerically homogeneous adducts
(via an endo transition state). The newly created ste-
acetic acid during the Ramberg-Ba¨cklund protocol is
presumably involved. In entry 4 (Table 1), the isomer-
ization of the enol silyl ether double bond to the more
conjugated location is assumed to be a base-mediated
event that occurs during the course of the ring contraction
step.
The sequence of reactions depicted in eq 4 represents
an interesting example of how this benzannulation
process can be profitably employed to rapidly assemble
structurally complex target molecules. Photocycloaddi-
tion of complex 1 with the methoxytetralone-derived
diene 915 afforded the tetracyclic adduct 1011 as a single
diastereomer in virtually quantitative yield. Subsequent
one-pot conversion via Ramberg-Ba¨cklund rearrange-
ment into the chrysene derivative 1111 completed the
sequence. Once again, the efficiency of the ring contrac-
tion step in this instance was dramatically improved by
employing N-iodosuccinimide in place of NCS as the
positive halogen source.
In summary, rapid access to a number of benzo-fused
polycyclic materials can be easily achieved employing a
sequence of steps initiated by a Cr(0)-mediated [6π + 4π]
cycloaddition of thiepin 1,1-dioxide with various diene
partners followed by a Ramberg-Ba¨cklund rearrange-
ment procedure.
reogenic centers in 511 and 711 are transferred to the
benzo-fused products 611 and 811 with complete integrity.
The reactions in eqs 2 and 3 also reveal that replacing
N-chlorosuccinimide (NCS) with N-iodosuccinimide (NIS)
during the Ramberg-Ba¨cklund step can facilitate dif-
ficult arene ring constructions. Indeed, efforts to convert
7 into 8 employing NCS were ineffectual. It appears that
steric congestion in the vicinity of the ring contraction
events can be overcome by the intervention of an iodi-
nating agent. In this regard, iodide is known to be a
superior leaving group in these types of transformations.8a
The results of several benzannulations employing
relatively simple diene partners are compiled in Table
1. Several points are worthy of note in this collection.
For example, the formation of the fully aromatized
naphthalene product in entry 1 (Table 1) is presumably
due to adventitious air oxidation. This is the only case
to date in which this apparently spontaneous dehydro-
genation has occurred. In contrast, direct conversion to
fully aromatic naphthalene was the anticipated outcome
of the sequence employing 1-acetoxybutadiene as the
diene partner (Entry 3). Elimination of the elements of
Ack n ow led gm en t. We thank the National Insti-
tutes of Health (GM-30771) for generous financial
support of this research.
Su p p or tin g In for m a tion Ava ila ble: Typical experimen-
tal procedures and complete spectroscopic data for all new
compounds (7 pages).
J O9616419
(15) Woski, S. A.; Koreeda, M. J . Org. Chem.1992, 57, 5736.