p-Cresyl 2,3-an­hydro-5-deoxy-5-phthal­imido-1-thio-[alpha]-D-lyxo­furan­oside

The crystal structure of the title compound, C₂₀H₁₇NO₄S, (I), was determined in order to compare the solution and solid-state conformations. The mol­ecule was synthesized as a building block for incorporation into oligosaccharides comprised of conformationally restricted furan­ose residues. The furan­ose ring adopts an envelope conformation with the ring O atom displaced above the plane (an ^OE conformation). The pseudorotational phase angle (P) is 88.6° and the puckering amplitude ([tau]_m) is 31.5°. The C₂-C₁-S-C(Ph) torsion angle is -163.2 (2)°, which places the aglycone in the exo-anomeric effect preferred position. The C1-S-C14 bond angle is 99.02 (13)° and the plane of the cresyl moiety is oriented nearly parallel to the four in-plane atoms of the furan­ose ring envelope. The orientation about the C4-C5 bond is gauche-gauche [Bock & Duus (1994). J. Carbohydr. Chem. 13, 513-543].

S1. Comment

NO COMMENT TEXT

S2. Experimental

p-Cresyl 1-thio-α-D-arabinofuranoside (0.5 g, 1.95 mmol) (D'Souza et al., 2000), triphenylphosphine (1.28 g, 4.88 mmol) and phthalamide (0.43 g, 2.92 mmol) were dissolved in tetrahydrofuran (20 ml) and the solution was stirred and cooled to 273 K. Diethyl azodicarboxylate (0.77 ml, 4.88 mmol) was added dropwise over a period of 10 min and the reaction mixture was stirred for another 30 min as it warmed to room temperature. The solution was concentrated to dryness under reduced pressure and the residue was purified by column chromatography using 4:1 petroleum ether/ethyl acetate as the eluant to give 560 mg (78%) of the product as a colourless solid. The product was recrystallized from a 1:1 dichloromethane/hexane (m.p. 416–419 K).

S3. Refinement

The correct enantiomer was chosen based on the known absolute configuration. There is a region containing disordered solvent, which appears to consist of three peaks situated along a line. As it was difficult to obtain a satisfactory model of this region in terms of a recognizable molecule, the density in this area was accounted for by the SQUEEZE program (Sluis & Spek, 1990) of PLATON (Spek, 1999). This program modifies the observed structure factors by subtracting the contributions to them from the electron density in the disordered region. This region occupies a total of 84%A⁻³ per unit cell and the electron density removed by the SQUEEZE procedure amounts to 5 electrons per unit cell. This disordered solvent molecule is located in a channel which runs parallel to the b axis.

Computing details

Data collection: COLLECT (Nonius, 1999); cell refinement: DENZO (Otwinowski & Minor, 1997); data reduction: DENZO; program(s) used to solve structure: SHELXS86 (Sheldrick, 1990); program(s) used to refine structure: SHELXL93 (Sheldrick, 1993).

p-Cresyl 2,3-anhydro-5-phthalimido-1-thio-α-D-lyxofuranoside

Crystal data

C20H17NO4S	F(000) = 384
Mr = 367.41	Dx = 1.311 Mg m^−3
Monoclinic, P21	Mo Kα radiation, λ = 0.71073 Å
a = 12.1660 (4) Å	Cell parameters from 11686 reflections
b = 5.5725 (2) Å	θ = 2.7–25.0°
c = 14.5413 (4) Å	µ = 0.20 mm^−1
β = 109.247 (2)°	T = 150 K
V = 930.73 (5) Å^3	Rod, colourless
Z = 2	0.23 × 0.12 × 0.06 mm

Data collection

Nonius KappaCCD diffractometer	2693 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.054
Graphite monochromator	θmax = 25.0°, θmin = 2.7°
ω scans	h = −14→14
11686 measured reflections	k = −6→6
3119 independent reflections	l = −17→17

Refinement

Refinement on F^2	Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: full	H-atom parameters constrained
R[F^2 > 2σ(F^2)] = 0.047	w = 1/[σ^2(Fo^2) + (0.0458P)^2 + 0.3896P] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.102	(Δ/σ)max < 0.001
S = 1.05	Δρmax = 0.21 e Å^−3
3119 reflections	Δρmin = −0.19 e Å^−3
237 parameters	Absolute structure: Flack (1983), 1286 Friedel pairs
1 restraint	Absolute structure parameter: 0.00 (11)
Primary atom site location: structure-invariant direct methods

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 on F² for ALL reflections except for 0 with very negative F² or flagged by the user for potential systematic errors. Weighted R-factors wR and all goodnesses of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The observed criterion of F² > σ(F²) is used only for calculating R(obs) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F² are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

The low-temperature data set was measured using an Oxford Cryosystems Cryostream Cooler. A quadrant of data was measured with a frame width of 1.0° and a redundancy of 3. By definition, a redundancy of 3 implies that 90% of the data have been measured at least 3 times.

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

	x	y	z	Uiso*/Ueq
S	0.09610 (7)	0.4476 (2)	0.31522 (6)	0.0574 (3)
O1	0.2849 (2)	0.4150 (4)	0.25527 (12)	0.0381 (5)
O2	0.4057 (2)	0.1138 (4)	0.38835 (14)	0.0400 (5)
O3	0.6607 (2)	0.3193 (4)	0.4350 (2)	0.0524 (6)
O4	0.4501 (2)	0.3764 (5)	0.1123 (2)	0.0598 (7)
N	0.5364 (2)	0.3886 (5)	0.2791 (2)	0.0393 (6)
C1	0.2152 (2)	0.2752 (6)	0.2964 (2)	0.0371 (7)
H1	0.1837	0.1315	0.2548	0.044*
C2	0.2960 (3)	0.1992 (6)	0.3938 (2)	0.0408 (8)
H2	0.2652	0.1397	0.4454	0.049*
C3	0.3962 (3)	0.3555 (5)	0.4177 (2)	0.0383 (7)
H3	0.4365	0.4086	0.4863	0.046*
C4	0.3735 (2)	0.5287 (5)	0.3339 (2)	0.0379 (7)
H4	0.3408	0.6800	0.3514	0.046*
C5	0.4755 (3)	0.5934 (6)	0.3003 (2)	0.0435 (8)
H5A	0.4466	0.6939	0.2410	0.052*
H5B	0.5315	0.6912	0.3514	0.052*
C6	0.6254 (3)	0.2689 (6)	0.3496 (2)	0.0403 (7)
C7	0.5186 (3)	0.2966 (6)	0.1857 (2)	0.0465 (8)
C8	0.5993 (3)	0.0890 (6)	0.1998 (3)	0.0525 (9)
C9	0.6165 (4)	−0.0782 (9)	0.1340 (3)	0.0728 (13)
H9	0.5728	−0.0736	0.0665	0.087*
C10	0.7020 (5)	−0.2530 (8)	0.1738 (4)	0.086 (2)
H10	0.7158	−0.3693	0.1310	0.104*
C11	0.7665 (4)	−0.2656 (8)	0.2700 (4)	0.0795 (13)
H11	0.8231	−0.3885	0.2926	0.095*
C12	0.7497 (3)	−0.1001 (7)	0.3347 (3)	0.0620 (10)
H12	0.7942	−0.1057	0.4019	0.074*
C13	0.6657 (3)	0.0741 (6)	0.2980 (2)	0.0465 (8)
C14	−0.0047 (2)	0.4353 (6)	0.1951 (2)	0.0419 (7)
C15	−0.0102 (3)	0.6190 (6)	0.1280 (2)	0.0434 (8)
H15	0.0422	0.7505	0.1459	0.052*
C16	−0.0915 (3)	0.6091 (6)	0.0365 (2)	0.0420 (7)
H16	−0.0948	0.7365	−0.0078	0.050*
C17	−0.1683 (2)	0.4213 (6)	0.0067 (2)	0.0363 (6)
C18	−0.1612 (3)	0.2385 (6)	0.0732 (2)	0.0415 (7)
H18	−0.2128	0.1059	0.0540	0.050*
C19	−0.0815 (3)	0.2430 (6)	0.1664 (2)	0.0435 (8)
H19	−0.0791	0.1159	0.2106	0.052*
C20	−0.2589 (3)	0.4124 (7)	−0.0926 (2)	0.0512 (8)
H20A	−0.3333	0.3607	−0.0868	0.077*
H20B	−0.2347	0.2985	−0.1336	0.077*
H20C	−0.2679	0.5723	−0.1223	0.077*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
S	0.0474 (5)	0.0789 (7)	0.0464 (5)	0.0142 (5)	0.0161 (4)	−0.0143 (5)
O1	0.0432 (10)	0.0395 (12)	0.0314 (9)	−0.0005 (11)	0.0122 (8)	0.0022 (10)
O2	0.0460 (12)	0.0298 (11)	0.0460 (12)	0.0021 (10)	0.0174 (9)	0.0049 (10)
O3	0.0546 (13)	0.063 (2)	0.0399 (13)	0.0016 (11)	0.0159 (10)	−0.0084 (11)
O4	0.076 (2)	0.069 (2)	0.0356 (13)	−0.0286 (14)	0.0197 (12)	0.0018 (12)
N	0.0475 (14)	0.039 (2)	0.0364 (13)	−0.0089 (12)	0.0210 (11)	−0.0034 (12)
C1	0.040 (2)	0.035 (2)	0.039 (2)	0.0013 (14)	0.0175 (14)	−0.0051 (14)
C2	0.046 (2)	0.041 (2)	0.041 (2)	0.0053 (15)	0.0218 (15)	0.0020 (14)
C3	0.046 (2)	0.041 (2)	0.0299 (15)	0.0018 (14)	0.0140 (13)	−0.0026 (13)
C4	0.045 (2)	0.031 (2)	0.038 (2)	−0.0008 (13)	0.0140 (14)	−0.0019 (13)
C5	0.050 (2)	0.035 (2)	0.045 (2)	−0.006 (2)	0.0163 (15)	0.005 (2)
C6	0.043 (2)	0.039 (2)	0.044 (2)	−0.0070 (15)	0.0221 (15)	−0.004 (2)
C7	0.061 (2)	0.055 (2)	0.031 (2)	−0.027 (2)	0.024 (2)	−0.004 (2)
C8	0.070 (2)	0.045 (2)	0.063 (2)	−0.024 (2)	0.051 (2)	−0.017 (2)
C9	0.098 (3)	0.076 (3)	0.073 (2)	−0.049 (3)	0.067 (2)	−0.034 (3)
C10	0.122 (4)	0.047 (3)	0.145 (5)	−0.027 (3)	0.118 (4)	−0.038 (3)
C11	0.098 (3)	0.053 (3)	0.126 (4)	−0.009 (2)	0.089 (3)	−0.012 (3)
C12	0.064 (2)	0.053 (2)	0.091 (3)	−0.002 (2)	0.054 (2)	0.000 (2)
C13	0.056 (2)	0.039 (2)	0.059 (2)	−0.009 (2)	0.038 (2)	−0.004 (2)
C14	0.0355 (15)	0.043 (2)	0.051 (2)	0.006 (2)	0.0194 (13)	−0.008 (2)
C15	0.042 (2)	0.028 (2)	0.068 (2)	−0.0084 (14)	0.030 (2)	−0.006 (2)
C16	0.046 (2)	0.033 (2)	0.052 (2)	0.002 (2)	0.024 (2)	0.005 (2)
C17	0.0364 (14)	0.031 (2)	0.048 (2)	0.0067 (14)	0.0233 (13)	0.0007 (15)
C18	0.041 (2)	0.029 (2)	0.060 (2)	−0.0043 (14)	0.024 (2)	−0.002 (2)
C19	0.049 (2)	0.034 (2)	0.054 (2)	0.004 (2)	0.025 (2)	0.008 (2)
C20	0.050 (2)	0.056 (2)	0.050 (2)	0.009 (2)	0.0188 (15)	−0.002 (2)

Geometric parameters (Å, º)

S—C14	1.774 (3)	C8—C9	1.400 (5)
S—C1	1.832 (3)	C9—C10	1.404 (7)
O1—C1	1.421 (3)	C9—H9	0.95
O1—C4	1.435 (3)	C10—C11	1.361 (7)
O2—C3	1.429 (4)	C10—H10	0.95
O2—C2	1.443 (4)	C11—C12	1.380 (6)
O3—C6	1.206 (4)	C11—H11	0.95
O4—C7	1.202 (4)	C12—C13	1.383 (5)
N—C6	1.392 (4)	C12—H12	0.95
N—C7	1.400 (4)	C14—C19	1.392 (5)
N—C5	1.448 (4)	C14—C15	1.400 (4)
C1—C2	1.494 (4)	C15—C16	1.373 (4)
C1—H1	1.00	C15—H15	0.95
C2—C3	1.445 (4)	C16—C17	1.374 (4)
C2—H2	1.00	C16—H16	0.95
C3—C4	1.507 (4)	C17—C18	1.387 (4)
C3—H3	1.00	C17—C20	1.501 (4)
C4—C5	1.521 (4)	C18—C19	1.384 (4)
C4—H4	1.00	C18—H18	0.95
C5—H5A	0.99	C19—H19	0.95
C5—H5B	0.99	C20—H20A	0.98
C6—C13	1.492 (4)	C20—H20B	0.98
C7—C8	1.487 (5)	C20—H20C	0.98
C8—C13	1.392 (5)
C14—S—C1	99.02 (13)	C13—C8—C9	119.6 (4)
C1—O1—C4	107.6 (2)	C13—C8—C7	108.7 (3)
C3—O2—C2	60.4 (2)	C9—C8—C7	131.6 (4)
C6—N—C7	111.9 (3)	C8—C9—C10	116.0 (4)
C6—N—C5	123.3 (2)	C8—C9—H9	122.0
C7—N—C5	124.7 (3)	C10—C9—H9	122.0
O1—C1—C2	104.9 (2)	C11—C10—C9	123.8 (4)
O1—C1—S	112.7 (2)	C11—C10—H10	118.1
C2—C1—S	108.2 (2)	C9—C10—H10	118.1
O1—C1—H1	110.28	C10—C11—C12	120.1 (5)
C2—C1—H1	110.3	C10—C11—H11	119.9
S—C1—H1	110.28	C12—C11—H11	119.9
O2—C2—C3	59.3 (2)	C11—C12—C13	117.6 (4)
O2—C2—C1	111.9 (2)	C11—C12—H12	121.2
C3—C2—C1	107.3 (3)	C13—C12—H12	121.2
O2—C2—H2	120.91	C12—C13—C8	122.9 (3)
C3—C2—H2	120.9	C12—C13—C6	129.8 (3)
C1—C2—H2	120.9	C8—C13—C6	107.3 (3)
O2—C3—C2	60.3 (2)	C19—C14—C15	118.7 (3)
O2—C3—C4	111.9 (2)	C19—C14—S	120.1 (3)
C2—C3—C4	106.0 (2)	C15—C14—S	121.1 (3)
O2—C3—H3	121.04	C16—C15—C14	120.0 (3)
C2—C3—H3	121.0	C16—C15—H15	120.0
C4—C3—H3	121.0	C14—C15—H15	120.0
O1—C4—C3	104.5 (2)	C15—C16—C17	122.3 (3)
O1—C4—C5	109.1 (2)	C15—C16—H16	118.9
C3—C4—C5	117.4 (2)	C17—C16—H16	118.9
O1—C4—H4	108.50	C16—C17—C18	117.4 (3)
C3—C4—H4	108.5	C16—C17—C20	122.4 (3)
C5—C4—H4	108.5	C18—C17—C20	120.2 (3)
N—C5—C4	114.2 (2)	C19—C18—C17	122.2 (3)
N—C5—H5A	108.70	C19—C18—H18	118.9
C4—C5—H5A	108.7	C17—C18—H18	118.9
N—C5—H5B	108.7	C18—C19—C14	119.5 (3)
C4—C5—H5B	108.7	C18—C19—H19	120.3
H5A—C5—H5B	107.6	C14—C19—H19	120.3
O3—C6—N	125.0 (3)	C17—C20—H20A	109.5
O3—C6—C13	128.5 (3)	C17—C20—H20B	109.5
N—C6—C13	106.4 (3)	H20A—C20—H20B	109.5
O4—C7—N	124.5 (3)	C17—C20—H20C	109.5
O4—C7—C8	130.0 (3)	H20A—C20—H20C	109.5
N—C7—C8	105.5 (3)	H20B—C20—H20C	109.5
C4—O1—C1—C2	−30.4 (3)	C5—N—C7—C8	−180.0 (2)
C4—O1—C1—S	87.1 (2)	O4—C7—C8—C13	177.1 (3)
C14—S—C1—O1	81.2 (2)	N—C7—C8—C13	−3.5 (3)
C14—S—C1—C2	−163.2 (2)	O4—C7—C8—C9	−2.7 (6)
C3—O2—C2—C3	0.0	N—C7—C8—C9	176.6 (3)
C3—O2—C2—C1	97.7 (3)	C13—C8—C9—C10	0.0 (5)
O1—C1—C2—O2	−45.4 (3)	C7—C8—C9—C10	179.8 (3)
S—C1—C2—O2	−166.0 (2)	C8—C9—C10—C11	−0.1 (5)
O1—C1—C2—C3	17.8 (3)	C9—C10—C11—C12	−0.1 (6)
S—C1—C2—C3	−102.8 (2)	C10—C11—C12—C13	0.4 (5)
C2—O2—C3—C2	0.0	C11—C12—C13—C8	−0.4 (5)
C2—O2—C3—C4	−96.5 (3)	C11—C12—C13—C6	177.6 (3)
O2—C2—C3—O2	0.0	C9—C8—C13—C12	0.2 (5)
C1—C2—C3—O2	−105.7 (2)	C7—C8—C13—C12	−179.6 (3)
O2—C2—C3—C4	106.5 (2)	C9—C8—C13—C6	−178.2 (3)
C1—C2—C3—C4	0.8 (3)	C7—C8—C13—C6	2.0 (3)
C1—O1—C4—C3	30.9 (3)	O3—C6—C13—C12	2.4 (5)
C1—O1—C4—C5	157.3 (2)	N—C6—C13—C12	−177.9 (3)
O2—C3—C4—O1	45.0 (3)	O3—C6—C13—C8	−179.4 (3)
C2—C3—C4—O1	−18.9 (3)	N—C6—C13—C8	0.3 (3)
O2—C3—C4—C5	−76.0 (3)	C1—S—C14—C19	87.2 (2)
C2—C3—C4—C5	−139.9 (3)	C1—S—C14—C15	−93.9 (3)
C6—N—C5—C4	−85.7 (3)	C19—C14—C15—C16	1.0 (4)
C7—N—C5—C4	98.5 (3)	S—C14—C15—C16	−177.9 (2)
O1—C4—C5—N	−66.1 (3)	C14—C15—C16—C17	−0.9 (4)
C3—C4—C5—N	52.5 (3)	C15—C16—C17—C18	0.1 (4)
C7—N—C6—O3	177.0 (3)	C15—C16—C17—C20	178.6 (3)
C5—N—C6—O3	0.8 (4)	C16—C17—C18—C19	0.7 (4)
C7—N—C6—C13	−2.7 (3)	C20—C17—C18—C19	−177.9 (3)
C5—N—C6—C13	−178.9 (2)	C17—C18—C19—C14	−0.6 (4)
C6—N—C7—O4	−176.8 (3)	C15—C14—C19—C18	−0.3 (4)
C5—N—C7—O4	−0.6 (4)	S—C14—C19—C18	178.7 (2)
C6—N—C7—C8	3.8 (3)