1,2,7,8-Tetra-O-acetyl­australine

The title compound, C₁₆H₂₃NO₈, was obtained during studies of australine derivatives. The molecular stereochemistry is similar to that reported for other australine derivatives even though there is no intermolecular hydrogen bonding in this case.

S1. Comment

The title compound, (I), was studied to confirm the stereochemistry as there was some ambiguity between the observed and published NMR spectra. It was isolated as an acylated precursor in the preparation of substituted australine derivatives (Furneaux et al., 1994). The structure consists of independent molecules with normal bond lengths and angles (Allen et al., 1992). There are no close intermolecular contacts and the methyl H atoms on C13 and C17 are disordered over two orientations.

The fused ring C1/C2/C3/N4/C7a is in an envelope conformation with flap atom C2 0.623 (8) Å from the C1/C7a/N4/C3 plane, and with Q(2) = 0.409 (5) Å and ϕ = 247 (1)° (Cremer & Pople, 1975). This conformation has been found in all previously determined australine structures (Furneaux et al., 1994; Denmark & Herbet, 1998; Nash et al., 1994) except one, namely 1,2,7-tri-O-acetyl-8-deoxy-8-fluoro-australine (Furneaux et al., 1994; hereafter WEJVOW), where the twist ring description based on C1—C2 applies [Q(2) = 0.453 Å and ϕ = 239°]. The fused ring N4/C5/C6/C7/C7a adopts the twist-ring conformation based on C5—C6, with Q(2) = 0.394 (6) Å and ϕ = 82.1 (8)°, very similar to that found in WEJVOW [Q(2) = 0.414 Å and ϕ = 83°]. We note the close stereochemical similarity with the published structures which indicates that for australine derivatives the molecular geometry is not perturbed by intermolecular hydrogen-bonding crystal-packing forces; for example, in casaurine (Nash et al., 1994), all five hydroxyl protons are involved in O—H···O hydrogen bonds.

S2. Experimental

Crystals of 1,2,7,8-tetra-O-acetylaustraline were obtained as a minor component following acetylation and chromatographic fractionation of the mother liquor remaining after crystallizing castanospermine from extracts of Castanospermine australe seeds.

S3. Refinement

All H atoms were constrained to an isotropic displacement parameter 1.2 times that of the U_eq value of their parent atom. No Friedel pairs were collected. The absolute configuration cannot be determined from this experiment and was assumed from the synthesis.

Computing details

Data collection: R3m Software (Siemens, 1983); cell refinement: R3m Software; data reduction: R3m Software; program(s) used to solve structure: SHELXS86 (Sheldrick, 1985); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); software used to prepare material for publication: SHELXL97.

(I)

Crystal data

C16H23NO8	F(000) = 380
Mr = 357.35	Dx = 1.367 Mg m^−3
Monoclinic, P21	Mo Kα radiation, λ = 0.71069 Å
a = 9.586 (3) Å	Cell parameters from 25 reflections
b = 8.279 (2) Å	θ = 4.9–14.2°
c = 11.096 (5) Å	µ = 0.11 mm^−1
β = 99.74 (2)°	T = 173 K
V = 867.9 (5) Å^3	Translucent, colourless
Z = 2	0.44 × 0.26 × 0.16 mm

Data collection

Siemens R3m/scintillation counter diffractometer	Rint = 0.026
Radiation source: fine-focus sealed tube	θmax = 25.0°, θmin = 2.2°
Graphite monochromator	h = 0→11
ω scans	k = 0→9
1794 measured reflections	l = −13→13
1648 independent reflections	3 standard reflections every 97 reflections
1190 reflections with I > 2σ(I)	intensity decay: none

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.053	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.108	H-atom parameters constrained
S = 1.01	w = 1/[σ^2(Fo^2) + (0.0442P)^2] where P = (Fo^2 + 2Fc^2)/3
1648 reflections	(Δ/σ)max < 0.001
228 parameters	Δρmax = 0.22 e Å^−3
1 restraint	Δρmin = −0.27 e Å^−3

Special details

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Refinement. Refinement of F² for observed reflections. Methyl H atoms on C13 and c17 were refined in two orientation sets.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq	Occ. (<1)
O1	0.4488 (3)	0.1870 (5)	0.1999 (3)	0.0230 (8)
O2	0.4176 (4)	−0.0022 (5)	0.3389 (3)	0.0275 (9)
O3	0.6802 (3)	0.1739 (5)	0.0381 (3)	0.0236 (8)
O4	0.5324 (5)	0.3446 (6)	−0.0757 (4)	0.0499 (12)
O5	0.8429 (4)	0.5629 (4)	0.1582 (4)	0.0287 (10)
O6	1.0267 (4)	0.6673 (5)	0.0856 (4)	0.0381 (10)
O7	0.7386 (4)	−0.0139 (4)	0.4296 (3)	0.0228 (9)
O8	0.6866 (4)	−0.1321 (5)	0.6003 (4)	0.0414 (11)
N4	0.7935 (4)	0.3287 (5)	0.3422 (4)	0.0214 (10)
C1	0.5988 (4)	0.1725 (7)	0.2361 (4)	0.0203 (11)
H1	0.6269	0.0561	0.2370	0.024*
C2	0.6736 (5)	0.2652 (6)	0.1480 (5)	0.0208 (12)
H2	0.6269	0.3721	0.1275	0.025*
C3	0.8223 (5)	0.2882 (6)	0.2208 (5)	0.0217 (12)
H3	0.8715	0.1813	0.2262	0.026*
C5	0.9026 (5)	0.2856 (7)	0.4457 (5)	0.0283 (13)
H5A	0.9625	0.3804	0.4734	0.034*
H5B	0.9638	0.1984	0.4227	0.034*
C6	0.8233 (5)	0.2283 (7)	0.5468 (5)	0.0272 (13)
H6A	0.8815	0.1534	0.6040	0.033*
H6B	0.7931	0.3203	0.5932	0.033*
C7	0.6966 (5)	0.1422 (6)	0.4719 (5)	0.0221 (13)
H7	0.6165	0.1317	0.5185	0.026*
C7A	0.6579 (5)	0.2507 (6)	0.3602 (5)	0.0219 (12)
H7A	0.5907	0.3361	0.3786	0.026*
C8	0.9140 (5)	0.4091 (6)	0.1690 (5)	0.0266 (13)
H8A	1.0067	0.4189	0.2236	0.032*
H8B	0.9309	0.3727	0.0877	0.032*
C10	0.3695 (5)	0.0857 (7)	0.2568 (5)	0.0259 (13)
C11	0.2161 (5)	0.0968 (8)	0.1977 (5)	0.0368 (16)
H11A	0.1597	0.0226	0.2387	0.055*
H11B	0.2066	0.0675	0.1111	0.055*
H11C	0.1823	0.2075	0.2047	0.055*
C12	0.6052 (5)	0.2281 (7)	−0.0677 (5)	0.0264 (13)
C13	0.6243 (6)	0.1182 (8)	−0.1718 (5)	0.0347 (16)
H13A	0.6899	0.0309	−0.1411	0.052*	0.17 (6)
H13B	0.6628	0.1800	−0.2339	0.052*	0.17 (6)
H13C	0.5326	0.0720	−0.2080	0.052*	0.17 (6)
H13D	0.5670	0.1577	−0.2476	0.052*	0.83 (6)
H13E	0.5941	0.0086	−0.1548	0.052*	0.83 (6)
H13F	0.7243	0.1166	−0.1807	0.052*	0.83 (6)
C14	0.9127 (5)	0.6843 (7)	0.1142 (5)	0.0259 (12)
C15	0.8318 (7)	0.8384 (8)	0.1081 (6)	0.0403 (16)
H15A	0.8824	0.9220	0.0702	0.060*
H15B	0.8221	0.8721	0.1910	0.060*
H15C	0.7377	0.8224	0.0592	0.060*
C16	0.7157 (5)	−0.1426 (7)	0.4995 (5)	0.0279 (13)
C17	0.7289 (6)	−0.2969 (7)	0.4312 (5)	0.0300 (14)
H17A	0.7535	−0.2719	0.3510	0.045*	0.25 (5)
H17B	0.6387	−0.3552	0.4202	0.045*	0.25 (5)
H17C	0.8033	−0.3641	0.4778	0.045*	0.25 (5)
H17D	0.7102	−0.3889	0.4816	0.045*	0.75 (5)
H17E	0.8250	−0.3057	0.4125	0.045*	0.75 (5)
H17F	0.6604	−0.2967	0.3549	0.045*	0.75 (5)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0232 (17)	0.020 (2)	0.026 (2)	0.0025 (17)	0.0026 (14)	0.0010 (18)
O2	0.035 (2)	0.025 (2)	0.023 (2)	−0.0033 (18)	0.0054 (16)	0.0083 (19)
O3	0.0339 (19)	0.021 (2)	0.0155 (19)	0.0048 (18)	0.0039 (14)	0.0012 (18)
O4	0.063 (3)	0.051 (3)	0.033 (2)	0.032 (3)	0.000 (2)	0.007 (2)
O5	0.040 (2)	0.014 (2)	0.036 (3)	0.0053 (17)	0.0189 (19)	0.0076 (18)
O6	0.033 (2)	0.024 (2)	0.061 (3)	0.004 (2)	0.0204 (19)	0.015 (2)
O7	0.031 (2)	0.017 (2)	0.021 (2)	0.0035 (16)	0.0045 (16)	0.0035 (17)
O8	0.070 (3)	0.027 (3)	0.032 (3)	0.002 (2)	0.022 (2)	0.002 (2)
N4	0.022 (2)	0.018 (3)	0.023 (3)	−0.0002 (19)	0.0017 (18)	0.001 (2)
C1	0.015 (2)	0.021 (3)	0.025 (3)	0.003 (2)	0.0019 (19)	0.006 (3)
C2	0.026 (3)	0.012 (3)	0.024 (3)	0.005 (2)	0.005 (2)	0.000 (2)
C3	0.027 (3)	0.014 (3)	0.025 (3)	−0.001 (2)	0.007 (2)	−0.001 (2)
C5	0.027 (3)	0.030 (3)	0.029 (3)	−0.005 (3)	0.007 (2)	0.002 (3)
C6	0.032 (3)	0.029 (4)	0.020 (3)	0.000 (2)	0.003 (2)	−0.002 (3)
C7	0.029 (3)	0.020 (3)	0.017 (3)	0.003 (2)	0.004 (2)	−0.003 (2)
C7A	0.026 (3)	0.017 (3)	0.023 (3)	0.004 (2)	0.004 (2)	0.002 (2)
C8	0.032 (3)	0.017 (3)	0.033 (4)	0.004 (3)	0.013 (2)	0.002 (3)
C10	0.026 (3)	0.023 (3)	0.031 (3)	−0.005 (3)	0.012 (2)	−0.011 (3)
C11	0.021 (3)	0.045 (4)	0.044 (4)	0.002 (3)	0.008 (2)	0.005 (3)
C12	0.031 (3)	0.025 (3)	0.023 (3)	−0.003 (3)	0.006 (2)	0.007 (3)
C13	0.037 (3)	0.046 (4)	0.020 (3)	−0.009 (3)	0.002 (2)	−0.005 (3)
C14	0.030 (3)	0.021 (3)	0.027 (3)	−0.001 (3)	0.007 (2)	0.002 (3)
C15	0.052 (4)	0.024 (4)	0.051 (4)	0.000 (3)	0.026 (3)	0.007 (3)
C16	0.035 (3)	0.021 (3)	0.028 (3)	0.003 (3)	0.006 (3)	0.004 (3)
C17	0.037 (3)	0.019 (3)	0.035 (4)	−0.004 (3)	0.010 (3)	0.000 (3)

Geometric parameters (Å, º)

O1—C10	1.357 (7)	C7—C7A	1.525 (7)
O1—C1	1.431 (5)	C7—H7	1.0000
O2—C10	1.196 (7)	C7A—H7A	1.0000
O3—C12	1.345 (6)	C8—H8A	0.9900
O3—C2	1.446 (6)	C8—H8B	0.9900
O4—C12	1.185 (7)	C10—C11	1.508 (7)
O5—C14	1.344 (6)	C11—H11A	0.9800
O5—C8	1.440 (6)	C11—H11B	0.9800
O6—C14	1.196 (5)	C11—H11C	0.9800
O7—C16	1.358 (6)	C12—C13	1.506 (8)
O7—C7	1.455 (6)	C13—H13A	0.9800
O8—C16	1.200 (6)	C13—H13B	0.9800
N4—C3	1.458 (6)	C13—H13C	0.9800
N4—C5	1.461 (6)	C13—H13D	0.9800
N4—C7A	1.494 (6)	C13—H13E	0.9800
C1—C2	1.515 (7)	C13—H13F	0.9800
C1—C7A	1.541 (7)	C14—C15	1.488 (8)
C1—H1	1.0000	C15—H15A	0.9800
C2—C3	1.527 (7)	C15—H15B	0.9800
C2—H2	1.0000	C15—H15C	0.9800
C3—C8	1.509 (7)	C16—C17	1.502 (8)
C3—H3	1.0000	C17—H17A	0.9800
C5—C6	1.533 (7)	C17—H17B	0.9800
C5—H5A	0.9900	C17—H17C	0.9800
C5—H5B	0.9900	C17—H17D	0.9800
C6—C7	1.527 (7)	C17—H17E	0.9800
C6—H6A	0.9900	C17—H17F	0.9800
C6—H6B	0.9900
C10—O1—C1	115.7 (4)	C10—C11—H11C	109.5
C12—O3—C2	117.9 (4)	H11A—C11—H11C	109.5
C14—O5—C8	115.7 (4)	H11B—C11—H11C	109.5
C16—O7—C7	115.6 (4)	O4—C12—O3	123.9 (5)
C3—N4—C5	116.6 (4)	O4—C12—C13	125.5 (5)
C3—N4—C7A	109.2 (4)	O3—C12—C13	110.5 (5)
C5—N4—C7A	108.2 (4)	C12—C13—H13A	109.5
O1—C1—C2	109.8 (4)	C12—C13—H13B	109.5
O1—C1—C7A	114.6 (4)	H13A—C13—H13B	109.5
C2—C1—C7A	102.8 (4)	C12—C13—H13C	109.5
O1—C1—H1	109.8	H13A—C13—H13C	109.5
C2—C1—H1	109.8	H13B—C13—H13C	109.5
C7A—C1—H1	109.8	C12—C13—H13D	109.5
O3—C2—C1	111.8 (4)	H13A—C13—H13D	141.1
O3—C2—C3	110.0 (4)	H13B—C13—H13D	56.3
C1—C2—C3	102.9 (4)	H13C—C13—H13D	56.3
O3—C2—H2	110.6	C12—C13—H13E	109.5
C1—C2—H2	110.6	H13A—C13—H13E	56.3
C3—C2—H2	110.6	H13B—C13—H13E	141.1
N4—C3—C8	114.4 (4)	H13C—C13—H13E	56.3
N4—C3—C2	102.2 (4)	H13D—C13—H13E	109.5
C8—C3—C2	115.6 (4)	C12—C13—H13F	109.5
N4—C3—H3	108.1	H13A—C13—H13F	56.3
C8—C3—H3	108.1	H13B—C13—H13F	56.3
C2—C3—H3	108.1	H13C—C13—H13F	141.1
N4—C5—C6	105.8 (4)	H13D—C13—H13F	109.5
N4—C5—H5A	110.6	H13E—C13—H13F	109.5
C6—C5—H5A	110.6	O6—C14—O5	122.7 (5)
N4—C5—H5B	110.6	O6—C14—C15	125.5 (5)
C6—C5—H5B	110.6	O5—C14—C15	111.7 (4)
H5A—C5—H5B	108.7	C14—C15—H15A	109.5
C7—C6—C5	101.2 (4)	C14—C15—H15B	109.5
C7—C6—H6A	111.5	H15A—C15—H15B	109.5
C5—C6—H6A	111.5	C14—C15—H15C	109.5
C7—C6—H6B	111.5	H15A—C15—H15C	109.5
C5—C6—H6B	111.5	H15B—C15—H15C	109.5
H6A—C6—H6B	109.4	O8—C16—O7	124.1 (6)
O7—C7—C7A	107.7 (4)	O8—C16—C17	125.8 (6)
O7—C7—C6	110.7 (4)	O7—C16—C17	110.1 (4)
C7A—C7—C6	103.2 (4)	C16—C17—H17A	109.5
O7—C7—H7	111.6	C16—C17—H17B	109.5
C7A—C7—H7	111.6	H17A—C17—H17B	109.5
C6—C7—H7	111.6	C16—C17—H17C	109.5
N4—C7A—C7	105.4 (4)	H17A—C17—H17C	109.5
N4—C7A—C1	105.0 (4)	H17B—C17—H17C	109.5
C7—C7A—C1	118.7 (5)	C16—C17—H17D	109.5
N4—C7A—H7A	109.1	H17A—C17—H17D	141.1
C7—C7A—H7A	109.1	H17B—C17—H17D	56.3
C1—C7A—H7A	109.1	H17C—C17—H17D	56.3
O5—C8—C3	108.7 (4)	C16—C17—H17E	109.5
O5—C8—H8A	110.0	H17A—C17—H17E	56.3
C3—C8—H8A	110.0	H17B—C17—H17E	141.1
O5—C8—H8B	110.0	H17C—C17—H17E	56.3
C3—C8—H8B	110.0	H17D—C17—H17E	109.5
H8A—C8—H8B	108.3	C16—C17—H17F	109.5
O2—C10—O1	123.8 (5)	H17A—C17—H17F	56.3
O2—C10—C11	126.2 (5)	H17B—C17—H17F	56.3
O1—C10—C11	110.0 (5)	H17C—C17—H17F	141.1
C10—C11—H11A	109.5	H17D—C17—H17F	109.5
C10—C11—H11B	109.5	H17E—C17—H17F	109.5
H11A—C11—H11B	109.5
C10—O1—C1—C2	168.1 (4)	C3—N4—C7A—C7	121.0 (4)
C10—O1—C1—C7A	−76.9 (6)	C5—N4—C7A—C7	−6.8 (5)
C12—O3—C2—C1	112.7 (5)	C3—N4—C7A—C1	−5.1 (5)
C12—O3—C2—C3	−133.7 (4)	C5—N4—C7A—C1	−133.0 (4)
O1—C1—C2—O3	−81.2 (5)	O7—C7—C7A—N4	−87.8 (5)
C7A—C1—C2—O3	156.5 (4)	C6—C7—C7A—N4	29.2 (5)
O1—C1—C2—C3	160.8 (4)	O7—C7—C7A—C1	29.3 (6)
C7A—C1—C2—C3	38.5 (5)	C6—C7—C7A—C1	146.4 (4)
C5—N4—C3—C8	−82.3 (6)	O1—C1—C7A—N4	−140.1 (4)
C7A—N4—C3—C8	154.7 (4)	C2—C1—C7A—N4	−21.0 (5)
C5—N4—C3—C2	151.9 (4)	O1—C1—C7A—C7	102.5 (5)
C7A—N4—C3—C2	29.0 (5)	C2—C1—C7A—C7	−138.4 (4)
O3—C2—C3—N4	−161.1 (4)	C14—O5—C8—C3	179.3 (4)
C1—C2—C3—N4	−41.8 (5)	N4—C3—C8—O5	−60.9 (6)
O3—C2—C3—C8	74.0 (6)	C2—C3—C8—O5	57.5 (6)
C1—C2—C3—C8	−166.7 (5)	C1—O1—C10—O2	5.8 (8)
C3—N4—C5—C6	−141.9 (4)	C1—O1—C10—C11	−171.9 (4)
C7A—N4—C5—C6	−18.4 (6)	C2—O3—C12—O4	−1.3 (7)
N4—C5—C6—C7	35.9 (5)	C2—O3—C12—C13	−179.8 (4)
C16—O7—C7—C7A	−151.5 (4)	C8—O5—C14—O6	0.0 (8)
C16—O7—C7—C6	96.4 (5)	C8—O5—C14—C15	−179.2 (5)
C5—C6—C7—O7	75.6 (5)	C7—O7—C16—O8	−12.8 (7)
C5—C6—C7—C7A	−39.3 (5)	C7—O7—C16—C17	166.0 (4)