(2aR*,5S*,6aS*,8aS*,E)-Ethyl 5-hy­droxy-7,7,8a-trimethyl-8-oxo-2,2a,6,6a,7,8,8a,8b-octa­hydro-1H-penta­leno[1,6-bc]oxepine-4-carboxyl­ate

Mehta, G.; Kumar, C.S.A.; Sen, S.

doi:10.1107/S1600536812046776

Volume 68
Part 12
Pages o3392-o3393
December 2012

Received 2 October 2012
Accepted 13 November 2012
Online 24 November 2012

Key indicators
Single-crystal X-ray study
T = 291 K
Mean (C-C) = 0.004 Å
R = 0.053
wR = 0.149
Data-to-parameter ratio = 15.2
Details

(2aR,5S,6aS,8aS,E)-Ethyl 5-hydroxy-7,7,8a-trimethyl-8-oxo-2,2a,6,6a,7,8,8a,8b-octahydro-1H-pentaleno[1,6-bc]oxepine-4-carboxylate

Goverdhan Mehta,^a ^*⁺ C. S. Ananda Kumar ^a and Saikat Sen ^a

^aDepartment of Organic Chemistry, Indian Institute of Science, Bangalore 560 012, India
Correspondence e-mail: gmsc@uohyd.ernet.in, gm@orgchem.iisc.ernet.in

The title compound, C₁₇H₂₄O₅, featuring a 2-carbethoxy-3-oxepanone unit in its intramolecularly O-HO hydrogen-bonded enol form, was obtained via [(CF₃CO₂)₂Rh]₂-catalysed intramolecular O-H bond insertion in the [alpha] -diazo- [omega] -hydroxy- [beta] -ketoester, ethyl 4-[(1S,3aS,6R,6aS)-6-hydroxy-2,2,3a-trimethyl-3-oxo-octahydropentalen-1-yl]-2-diazo-3-oxobutanoate. The seven-membered oxacyclic ring, thus constructed on a cis-fused diquinane platform, was found to adopt a distorted boat-sofa conformation.

Related literature

For rhodium carbenoid-mediated intermolecular O-H insertion reactions and their application to natural product synthesis, see: Paulissen et al. (1973); Cox et al. (1994); Haigh (1994); Aller et al. (1995); Shi et al. (1995); Bulugahapitiya et al. (1997); Moody & Miller (1998); Nelson et al. (2000); Medeiros & Wood (2010); Freeman et al. (2010); Morton et al. (2012). For rhodium-catalysed intramolecular O-H insertion reactions, see: Paulissen et al. (1974); Moyer et al. (1985); Moody & Taylor (1987); Heslin & Moody (1988); Davies et al. (1990); Moody et al. (1992); Sarabia-Garciá et al. (1994); Padwa & Sá (1999); Im et al. (2005). For reviews on rhodium-mediated C-H insertion reactions, see: Doyle et al. (2010); Davies & Morton (2011). For the construction of an angularly fused triquinane skeleton via Rh^II-catalysed intramolecular C-H insertion, see: Srikrishna et al. (2012). For the isolation and synthesis of penifulvin A, see: Shim et al. (2006); Gaich & Mulzer (2009); Mehta & Khan (2012). For the application of p-acetamidobenzenesulfonyl azide as a diazo transfer reagent, see: Baum et al. (1987). For ring conformations, see: Cremer & Pople (1975); Boessenkool & Boeyens (1980).

Experimental

Crystal data

C₁₇H₂₄O₅
M_r = 308.36
Orthorhombic, P b c a
a = 8.447 (5) Å
b = 18.454 (14) Å
c = 21.735 (15) Å
V = 3388 (4) Å³
Z = 8
Mo K radiation
= 0.09 mm^-1
T = 291 K
0.20 × 0.18 × 0.08 mm

Data collection

Bruker APEXII CCD diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 2003) T_min = 0.983, T_max = 0.993
14606 measured reflections
3153 independent reflections
1408 reflections with I > 2(I)
R_int = 0.087

Refinement

R[F² > 2(F²)] = 0.053
wR(F²) = 0.149
S = 0.89
3153 reflections
207 parameters
H atoms treated by a mixture of independent and constrained refinement
_max = 0.17 e Å^-3
_min = -0.17 e Å^-3

Table 1
Hydrogen-bond geometry (Å, °)

D-HA	D-H	HA	DA	D-HA
O2-H2OO4	0.93 (3)	1.69 (3)	2.565 (4)	155 (3)

Data collection: APEX2 (Bruker, 2007); cell refinement: SAINT (Bruker, 2007); data reduction: SAINT; program(s) used to solve structure: SIR92 (Altomare et al., 1994); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012); software used to prepare material for publication: PLATON (Spek, 2009).

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: DS2220 ).

Acknowledgements

We thank the Department of Science and Technology (DST), India, for the CCD facility at the Indian Institute of Science (IISc), Bangalore. CSAK thanks the University Grants Commission for the award of a Dr D. S. Kothari post-doctoral fellowship. GM thanks the Government of India for the award of a National Research Professorship and acknowledges the current research support from the Eli Lilly and Jubilant-Bhartia Foundations.

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