Abstract
Different protective groups for the phenolic oxygen were investigated
in the molybdenum pentachloride-mediated dehydro-dimerization reaction.
Cyclic acetals and ketals, triisopropylsilyl and alkoxycarbonylmethyl
moieties are compatible with the strong acidic reaction conditions.
Key words
biaryls - coupling - dimerizations - protective
groups - molybdenum
References
1a
Waldvogel SR.
Fröhlich R.
Schalley CA.
Angew. Chem.
Int. Ed.
2000,
39:
2472
1b
Waldvogel SR.
Wartini AR.
Rasmussen PH.
Rebek J.
Tetrahedron Lett.
1999,
40:
3515
2 Kramer, B.; Averhoff, A.; Waldvogel,
S. R. Angew. Chem. Int. Ed. 2002, 41: in
press.
3
Waldvogel SR.
Aits E.
Holst C.
Fröhlich R.
Chem. Commun.
2002,
1278
4
Waldvogel SR.
Synlett
2002,
622
5
Kumar S.
Manickham M.
Chem. Commun.
1997,
1615
6
Green TW.
Wuts GM. In
Protective
Groups in Organic Synthesis
Wiley-Interscience;
New
York:
1999.
7
Takada T.
Arisawa M.
Gyoten M.
Hamada R.
Tohma H.
Kita Y.
J. Org. Chem.
1998,
63:
7698
8
Ogura K.
Tsuchihashi G.
Tetrahedron Lett.
1971,
12:
3151
9
Weertunga G.
Jaworska-Sobiesiak A.
Horne S.
Russell R.
Can. J. Chem.
1987,
65:
2019
10
Benigni JD.
Minnis RL.
J. Heterocycl. Chem.
1965,
2:
307
11
Arcoleo A.
Garofano T.
Ann. Chim. (Rome, Italy)
1957,
47:
1142
12
Srikishna A.
Rao MS.
Tetrahedron Lett.
2001,
42:
5781
13
Larock RC.
Babu S.
Tetrahedron
1987,
43:
2013
14a
Nelson TD.
Crouch RD.
Synthesis
1996,
1031
14b
Davies JS.
Higginbotham CL.
Tremeer EJ.
Brown C.
Treadgold RC.
J. Chem. Soc.,
Perkin Trans. 1
1992,
3043
15
Laatsch H.
Liebigs
Ann. Chem.
1980,
140
16
Laatsch H.
Z.
Naturforsch., B: Chem. Sci.
1985,
40:
534
17 X-ray crystal structure analysis of 4: formula C26H30O6 M = 438.50
colorless crystal 0.35 × 0.30 × 0.10
mm a = 11.923(2) b = 12.352(2) c = 16.974(2) Å α = 96.80(1) β = 92.64(2) γ = 112.76(1)° V = 2277.4(6) Å3 ρcalc = 1.279 gcm-3 µ = 7.34
cm-1 empirical absorption correction
via ψ scan data (0.783 ≤ T ≤ 0.930) Z = 4 triclinic
space group P1bar (No. 2) λ = 1.54178 Å T = 223 K ω/2θ scans
9478 reflections collected (+h ±k ±l) [(sinθ)/λ] = 0.62 Å-1
9040 independent (Rint = 0.026)
and 7595 observed reflections [I ≥ 2 σ(I)] 595 refined parameters R = 0.047 wR2 = 0.134 max.
residual electron density 0.30 (-0.24) e Å-3 two independent
molecules in the asymmetric unit hydrogens calculated and refined
as riding atoms.
Data set was collected with an Enraf Nonius
CAD4 diffractometer. Programs used: data collection Express (Nonius
B.V. 1994) data reduction MolEN (K. Fair 1990) structure soln SHELXS-97
(Sheldrick, G. M. Acta Cryst. 1990, A46, 467)
structure refinement SHELXL-97 (Sheldrick, G. M. Universität
Göttingen, 1997) graphics POV-Ray
3.2.
Crystallographic data (excluding structure factors)
for the structure reported in this paper have been deposited with
the Cambridge Crystallographic Data Centre as supplementary publication
CCDC 191456. Copies of the data can be obtained free of charge on
application to The Director CCDC 12 Union Road CambridgeCB2 1EZ
UK [fax: +44(1223)336033 e-mail: deposit@ccdc.cam.ac.uk].
18 Structure of 4:
The chemical shifts for the structure were assigned by long range
coupling experiments and refer to the following numbering (Figure
[2]
).
19 For a multi-step synthesis of 1f, see: Freudenberg K.
Müller HG.
Liebigs Ann.
Chem.
1953,
584:
40
