RSS-Feed abonnieren
PDF herunterladen
DOI: 10.1055/s-2008-1078057
An Approach to Benzannelated [5,6]-Spiroketals
Publikationsverlauf
Publikationsdatum:
12. September 2008 (online)
Abstract
Heating a variety of 2-hydroxybenzyl acetates bearing a range functional groups on the 4- or 5-position of the aromatic ring at 100 ˚C in neat γ-methylene-γ-butyrolactone (1.0 M) for 20 hours gives a series of benzannelated [5,6]-spiroketals in 75-89% yield.
Key words
Diels-Alder reactions - spiro compounds - heterocycles - natural products - ortho-quinone methide
- 1a
Stierle AA.Stierle DB.Kelly K. J. Org. Chem. 2006, 71: 5357 - 1b
Brasholz M.Sörgel S.Azap C.Reißig H.-U. Eur. J. Org. Chem. 2007, 3801 - 2
Ueno T.Takahashi H.Oda M.Mizunuma M.Yokoyama A.Goto Y.Mizushina Y.Sakaguchi K.Hayashi H. Biochemistry 2000, 39: 5995 - 3a
Tsang KY.Brimble MA. Tetrahedron 2007, 63: 6015 - 3b
Sörgel S.Azap C.Reißig H.-U. Org. Lett. 2006, 8: 4875 - 3c
Waters SP.Fennie MW.Kozlowski MC. Org. Lett. 2006, 8: 3243 - 3d
Waters SP.Fennie MW.Kozlowski MC. Tetrahedron Lett. 2006, 47: 5409 - 3e
Tsang KY.Brimble MA.Bremner JB. Org. Lett. 2003, 5: 4425 - 3f
Capecchi T.de Koning CB.Michael JP. J. Chem. Soc., Perkin Trans. 1 2000, 2681 - 3g
Capecchi T.De Koning CB.Michael JP. Tetrahedron Lett. 1998, 39: 5429 - For a [3+2]-cycloaddition approach, see:
- 4a
Wu K.-L.Wilkinson S.Reich NO.Pettus TRR. Org. Lett. 2007, 9: 5537 - 4b
Lindsey CC.Wu KL.Pettus TRR. Org. Lett. 2006, 8: 2365 - 5 For an excellent review of ortho-quinone methides, see:
Van De Water RW.Pettus TRR. Tetrahedron 2002, 58: 5367 - 6a
Bray CD. Org. Biomol. Chem. 2008, 6: 2815 - 6b For a closely related
process, see:
Marsini MA.Huang Y.Lindsey CC.Wu K.-L.Pettus TRR. Org. Lett. 2008, 10: 1477 - 7
Loubinoux B.Miazimbakana J.Gerardin P. Tetrahedron Lett. 1989, 30: 1939 - 8
Rodriguez R.Moses JE.Adlington RM.Baldwin JE. Org. Biomol. Chem. 2005, 3: 3488 - 9a
Zhou G.Zhu J.Xie Z.Li Y. Org. Lett. 2008, 10: 721 - 9b See also:
Zhou G.Zheng D.Da S.Xie Z.Li Y. Tetrahedron Lett. 2006, 47: 3349 - 11 These were generally prepared in
good yield by selective primary acetylation of the corresponding
2-hydroxybenzyl alcohols using Ac2O (1.05 equiv) in the
presence of catalytic BF3˙OEt2 (5
mol%), see:
Weinert EE.Frankenfield KN.Rokita SE. Chem. Res. Toxicol. 2005, 18: 1364 - 12
Mixich Z. Monatsh. Chem. 1965, 96: 220
References and Notes
General Procedure:
2-Hydroxybenzyl acetate (8a; 40 mg, 0.24
mmol) in γ-methylene-γ-butyrolactone (0.24 mL,
1.0
M) was heated at 100 ˚C for 20 h. The cooled reaction mixture
was purified by flash column chromatography (SiO2, 25% → 30% EtOAc
in PE) to give 9a as a white solid (36
mg, 84%); mp 107-108 ºC (lit.¹² 106 ºC); R
f
0.26 (EtOAc-PE,
3:7). IR: 2961, 2920, 1776 (C=O), 1582, 1489, 1447, 1251,
1220, 1170, 1093, 1055 cm-¹. ¹H
NMR (400 MHz, CDCl3): δ = 7.07-7.17
(m, 2 H, 2 × ArCH), 6.93 (dt, J = 7.4,
1.1 Hz, 1 H, ArCH), 6.81 (dd, J = 8.1,
1.1 Hz, 1 H, ArCH), 3.06-3.18 (m, 1 H, 1 H of CH2),
2.91-3.04 (m, 1 H, 1 H of CH2), 2.79 (ddd, J = 16.5, 6.0, 2.5 Hz, 1 H,
1 H of CH2), 2.64 (ddd, J = 17.6,
9.5, 2.5 Hz, 1 H, 1 H of CH2), 2.52 (ddd, J = 13.1, 9.5, 2.5 Hz, 1 H,
1 H of CH2), 2.19-2.35 (m, 2 H, 2 × 1
H of CH2), 2.06-2.16 (m, 1 H, 1 H of CH2). ¹³C NMR
(100 MHz, CDCl3): δ = 175.5 (C=O),
151.4 (ArCO), 129.0 (ArCH), 127.5 (ArCH), 121.6 (ArCH), 120.9 (ArC), 116.7
(ArCH), 106.2 (OCO), 33.8 (CH2), 30.1 (CH2),
28.2 (CH2), 21.4 (CH2). HRMS (EI): m/z [M + Na]+ calcd
for C12H12O3Na: 227.0684; found:
227.0690.