Benzyl (2S)-2-tert-butoxy­carbonyl­amino-5-(2-furyl)-5-oxopentanoate

The title compound, C₂₁H₂₅NO₆, prepared using a procedure for the synthesis of enantiomerically pure 5-oxo-α-amino acids, has three fully extended substituents on the central α-C atom of the amino acid. Relatively weak N—H...O=C hydrogen bonds (N...O > 3 Å) link the mol­ecules into chains.

Key indicators

• Single-crystal X-ray study
• T = 160 K
• Mean [sigma](C-C) = 0.004 Å
• R factor = 0.031
• wR factor = 0.081
• Data-to-parameter ratio = 6.9

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry

General Notes



REFLT_03
         From the CIF: _diffrn_reflns_theta_max           25.00
         From the CIF: _reflns_number_total               1786
         Count of symmetry unique reflns         1789
         Completeness (_total/calc)             99.83%
         TEST3: Check Friedels for noncentro structure
         Estimate of Friedel pairs measured         0
         Fraction of Friedel pairs measured     0.000
         Are heavy atom types Z>Si present           no
          Please check that the estimate of the number of Friedel pairs is
          correct. If it is not, please give the correct count in the
          _publ_section_exptl_refinement section of the submitted CIF.

---

Computing details

Data collection: DIF4 (Stoe & Cie, 1988); cell refinement: DIF4; data reduction: local programs; program(s) used to solve structure: SHELXTL (Sheldrick, 2001); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and local programs.

Benzyl (2S)-2-tert-butoxycarbonylamino-5-(2-furyl)-5-oxopentanoate

Crystal data

C21H25NO6	Z = 1
Mr = 387.42	F(000) = 206
Triclinic, P1	Dx = 1.266 Mg m^−3
a = 5.200 (2) Å	Mo Kα radiation, λ = 0.71073 Å
b = 10.132 (4) Å	Cell parameters from 32 reflections
c = 10.768 (4) Å	θ = 10.7–12.5°
α = 65.66 (2)°	µ = 0.09 mm^−1
β = 83.87 (2)°	T = 160 K
γ = 79.63 (3)°	Plate, colourless
V = 508.1 (3) Å^3	0.56 × 0.52 × 0.20 mm

Data collection

Stoe–Siemens four-circle diffractometer	Rint = 0.038
Radiation source: fine-focus sealed tube	θmax = 25.0°, θmin = 3.6°
Graphite monochromator	h = −6→6
ω/θ scans with on–line profile fitting (Clegg, 1981)	k = −10→12
1795 measured reflections	l = −5→12
1786 independent reflections	5 standard reflections every 60 min
1729 reflections with I > 2σ(I)	intensity decay: 2%

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.031	H-atom parameters constrained
wR(F^2) = 0.081	w = 1/[σ^2(Fo^2) + (0.0533P)^2 + 0.0741P] where P = (Fo^2 + 2Fc^2)/3
S = 1.05	(Δ/σ)max < 0.001
1786 reflections	Δρmax = 0.18 e Å^−3
257 parameters	Δρmin = −0.23 e Å^−3
3 restraints	Extinction correction: SHELXTL, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.031 (8)

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

	x	y	z	Uiso*/Ueq
C1	0.6528 (5)	0.3489 (4)	−0.0269 (3)	0.0422 (7)
H1A	0.5683	0.3256	−0.0909	0.063*
H1B	0.7823	0.2652	0.0237	0.063*
H1C	0.7400	0.4349	−0.0775	0.063*
C2	0.3166 (5)	0.2478 (3)	0.1555 (3)	0.0373 (6)
H2A	0.2236	0.2239	0.0947	0.056*
H2B	0.1920	0.2688	0.2223	0.056*
H2C	0.4492	0.1645	0.2031	0.056*
C3	0.2547 (5)	0.5159 (3)	−0.0034 (3)	0.0348 (6)
H3A	0.1082	0.5264	0.0588	0.052*
H3B	0.1889	0.5052	−0.0802	0.052*
H3C	0.3419	0.6029	−0.0376	0.052*
C4	0.4482 (4)	0.3812 (3)	0.0723 (2)	0.0279 (5)
C5	0.4911 (4)	0.4462 (3)	0.2637 (2)	0.0248 (5)
C6	0.5796 (4)	0.5161 (2)	0.4413 (2)	0.0232 (5)
H6	0.4254	0.4686	0.4919	0.028*
C7	0.4958 (4)	0.6809 (3)	0.3786 (2)	0.0252 (5)
C8	0.1986 (5)	0.8740 (3)	0.4062 (3)	0.0331 (5)
H8A	0.1423	0.9138	0.3110	0.040*
H8B	0.3386	0.9270	0.4093	0.040*
C9	−0.0295 (5)	0.8945 (3)	0.4985 (3)	0.0290 (5)
C10	−0.0795 (6)	0.7840 (3)	0.6234 (3)	0.0374 (6)
H10	0.0329	0.6926	0.6538	0.045*
C11	−0.2949 (7)	0.8074 (3)	0.7041 (3)	0.0523 (8)
H11	−0.3289	0.7314	0.7896	0.063*
C12	−0.4602 (6)	0.9397 (4)	0.6614 (3)	0.0486 (7)
H12	−0.6096	0.9539	0.7161	0.058*
C13	−0.4065 (6)	1.0510 (3)	0.5388 (3)	0.0431 (7)
H13	−0.5160	1.1433	0.5101	0.052*
C14	−0.1920 (5)	1.0283 (3)	0.4572 (3)	0.0357 (6)
H14	−0.1566	1.1052	0.3725	0.043*
C15	0.7929 (4)	0.4803 (2)	0.5433 (2)	0.0246 (5)
H15A	0.9520	0.5197	0.4933	0.030*
H15B	0.7319	0.5287	0.6066	0.030*
C16	0.8605 (4)	0.3166 (3)	0.6246 (2)	0.0277 (5)
H16A	0.7005	0.2774	0.6734	0.033*
H16B	0.9228	0.2687	0.5610	0.033*
C17	1.0680 (4)	0.2785 (3)	0.7270 (2)	0.0257 (5)
C18	1.0941 (4)	0.1309 (3)	0.8343 (2)	0.0267 (5)
C19	0.9463 (5)	0.0228 (3)	0.8754 (3)	0.0414 (6)
H19	0.7922	0.0227	0.8353	0.050*
C20	1.0712 (7)	−0.0924 (3)	0.9926 (3)	0.0515 (8)
H20	1.0154	−0.1842	1.0462	0.062*
C21	1.2811 (6)	−0.0447 (3)	1.0113 (3)	0.0479 (7)
H21	1.4007	−0.0997	1.0819	0.058*
N	0.6703 (3)	0.4612 (2)	0.3367 (2)	0.0260 (4)
H0	0.8386	0.4382	0.3213	0.031*
O1	0.6072 (3)	0.41020 (19)	0.16225 (16)	0.0299 (4)
O2	0.2558 (3)	0.4606 (2)	0.28993 (18)	0.0373 (5)
O3	0.5954 (4)	0.7660 (2)	0.27926 (19)	0.0424 (5)
O4	0.2950 (3)	0.71995 (17)	0.45144 (17)	0.0294 (4)
O5	1.2087 (3)	0.3663 (2)	0.72065 (18)	0.0362 (4)
O6	1.3017 (4)	0.0911 (2)	0.91733 (18)	0.0387 (4)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.0274 (12)	0.076 (2)	0.0448 (15)	−0.0088 (13)	0.0020 (11)	−0.0461 (15)
C2	0.0358 (14)	0.0410 (14)	0.0415 (14)	−0.0097 (11)	−0.0049 (11)	−0.0205 (12)
C3	0.0298 (13)	0.0424 (14)	0.0342 (13)	−0.0092 (11)	−0.0038 (10)	−0.0153 (11)
C4	0.0206 (11)	0.0453 (14)	0.0294 (11)	−0.0089 (9)	−0.0019 (9)	−0.0249 (10)
C5	0.0178 (10)	0.0354 (11)	0.0264 (11)	−0.0064 (9)	0.0019 (8)	−0.0171 (9)
C6	0.0173 (10)	0.0349 (12)	0.0225 (10)	−0.0040 (9)	0.0016 (8)	−0.0171 (9)
C7	0.0176 (10)	0.0375 (12)	0.0217 (11)	−0.0028 (9)	−0.0013 (8)	−0.0135 (10)
C8	0.0332 (13)	0.0271 (12)	0.0358 (13)	−0.0028 (10)	0.0036 (10)	−0.0112 (10)
C9	0.0282 (12)	0.0297 (11)	0.0368 (13)	−0.0075 (9)	−0.0019 (10)	−0.0195 (10)
C10	0.0434 (15)	0.0295 (12)	0.0404 (14)	−0.0042 (11)	0.0110 (12)	−0.0187 (11)
C11	0.064 (2)	0.0439 (16)	0.0527 (18)	−0.0187 (15)	0.0267 (15)	−0.0254 (14)
C12	0.0401 (16)	0.0602 (19)	0.0630 (19)	−0.0119 (13)	0.0160 (14)	−0.0446 (16)
C13	0.0344 (13)	0.0440 (15)	0.0617 (18)	0.0033 (11)	−0.0031 (12)	−0.0354 (14)
C14	0.0312 (13)	0.0350 (13)	0.0435 (14)	−0.0012 (10)	−0.0046 (11)	−0.0192 (11)
C15	0.0225 (11)	0.0296 (11)	0.0261 (11)	−0.0035 (8)	−0.0030 (8)	−0.0151 (9)
C16	0.0231 (11)	0.0299 (12)	0.0336 (12)	−0.0028 (9)	−0.0060 (9)	−0.0156 (10)
C17	0.0184 (10)	0.0350 (12)	0.0261 (11)	−0.0017 (9)	0.0023 (8)	−0.0165 (9)
C18	0.0214 (11)	0.0359 (12)	0.0260 (11)	0.0024 (9)	−0.0005 (8)	−0.0183 (10)
C19	0.0351 (14)	0.0320 (13)	0.0527 (16)	−0.0025 (11)	0.0016 (12)	−0.0144 (12)
C20	0.063 (2)	0.0321 (14)	0.0472 (16)	−0.0042 (13)	0.0079 (14)	−0.0078 (12)
C21	0.0576 (19)	0.0458 (16)	0.0319 (14)	0.0062 (14)	−0.0070 (13)	−0.0115 (12)
N	0.0149 (9)	0.0411 (10)	0.0288 (9)	−0.0019 (8)	0.0009 (7)	−0.0223 (8)
O1	0.0168 (8)	0.0527 (10)	0.0334 (9)	−0.0070 (7)	0.0005 (6)	−0.0299 (8)
O2	0.0166 (8)	0.0695 (13)	0.0406 (10)	−0.0080 (8)	0.0026 (7)	−0.0371 (10)
O3	0.0360 (10)	0.0421 (10)	0.0318 (10)	0.0010 (8)	0.0079 (8)	−0.0025 (8)
O4	0.0272 (9)	0.0276 (8)	0.0335 (9)	−0.0054 (7)	0.0078 (7)	−0.0140 (7)
O5	0.0311 (9)	0.0453 (10)	0.0338 (9)	−0.0149 (8)	−0.0068 (7)	−0.0125 (8)
O6	0.0393 (10)	0.0450 (11)	0.0300 (9)	0.0016 (8)	−0.0121 (7)	−0.0138 (8)

Geometric parameters (Å, º)

C1—H1A	0.980	C9—C14	1.387 (4)
C1—H1B	0.980	C10—H10	0.950
C1—H1C	0.980	C10—C11	1.390 (4)
C1—C4	1.516 (3)	C11—H11	0.950
C2—H2A	0.980	C11—C12	1.382 (5)
C2—H2B	0.980	C12—H12	0.950
C2—H2C	0.980	C12—C13	1.378 (5)
C2—C4	1.517 (4)	C13—H13	0.950
C3—H3A	0.980	C13—C14	1.390 (4)
C3—H3B	0.980	C14—H14	0.950
C3—H3C	0.980	C15—H15A	0.990
C3—C4	1.518 (4)	C15—H15B	0.990
C4—O1	1.484 (3)	C15—C16	1.516 (3)
C5—N	1.347 (3)	C16—H16A	0.990
C5—O1	1.342 (3)	C16—H16B	0.990
C5—O2	1.222 (3)	C16—C17	1.510 (3)
C6—H6	1.000	C17—C18	1.458 (3)
C6—C7	1.519 (3)	C17—O5	1.227 (3)
C6—C15	1.535 (3)	C18—C19	1.348 (4)
C6—N	1.452 (3)	C18—O6	1.371 (3)
C7—O3	1.199 (3)	C19—H19	0.950
C7—O4	1.340 (3)	C19—C20	1.436 (4)
C8—H8A	0.990	C20—H20	0.950
C8—H8B	0.990	C20—C21	1.335 (5)
C8—C9	1.506 (4)	C21—H21	0.950
C8—O4	1.438 (3)	C21—O6	1.346 (4)
C9—C10	1.385 (4)	N—H0	0.880
H1A—C1—H1B	109.5	H10—C10—C11	120.1
H1A—C1—H1C	109.5	C10—C11—H11	119.6
H1A—C1—C4	109.5	C10—C11—C12	120.8 (3)
H1B—C1—H1C	109.5	H11—C11—C12	119.6
H1B—C1—C4	109.5	C11—C12—H12	120.3
H1C—C1—C4	109.5	C11—C12—C13	119.4 (3)
H2A—C2—H2B	109.5	H12—C12—C13	120.3
H2A—C2—H2C	109.5	C12—C13—H13	120.0
H2A—C2—C4	109.5	C12—C13—C14	120.1 (3)
H2B—C2—H2C	109.5	H13—C13—C14	120.0
H2B—C2—C4	109.5	C9—C14—C13	120.5 (3)
H2C—C2—C4	109.5	C9—C14—H14	119.7
H3A—C3—H3B	109.5	C13—C14—H14	119.7
H3A—C3—H3C	109.5	C6—C15—H15A	109.3
H3A—C3—C4	109.5	C6—C15—H15B	109.3
H3B—C3—H3C	109.5	C6—C15—C16	111.75 (18)
H3B—C3—C4	109.5	H15A—C15—H15B	107.9
H3C—C3—C4	109.5	H15A—C15—C16	109.3
C1—C4—C2	110.5 (2)	H15B—C15—C16	109.3
C1—C4—C3	110.2 (2)	C15—C16—H16A	109.0
C1—C4—O1	102.53 (17)	C15—C16—H16B	109.0
C2—C4—C3	112.7 (2)	C15—C16—C17	112.83 (19)
C2—C4—O1	109.59 (19)	H16A—C16—H16B	107.8
C3—C4—O1	110.82 (19)	H16A—C16—C17	109.0
N—C5—O1	110.72 (18)	H16B—C16—C17	109.0
N—C5—O2	123.8 (2)	C16—C17—C18	116.5 (2)
O1—C5—O2	125.5 (2)	C16—C17—O5	122.1 (2)
H6—C6—C7	108.6	C18—C17—O5	121.3 (2)
H6—C6—C15	108.6	C17—C18—C19	133.1 (2)
H6—C6—N	108.6	C17—C18—O6	116.3 (2)
C7—C6—C15	108.57 (17)	C19—C18—O6	110.6 (2)
C7—C6—N	111.01 (18)	C18—C19—H19	127.3
C15—C6—N	111.47 (17)	C18—C19—C20	105.4 (3)
C6—C7—O3	125.6 (2)	H19—C19—C20	127.3
C6—C7—O4	110.43 (18)	C19—C20—H20	126.8
O3—C7—O4	123.9 (2)	C19—C20—C21	106.4 (3)
H8A—C8—H8B	108.4	H20—C20—C21	126.8
H8A—C8—C9	110.0	C20—C21—H21	124.3
H8A—C8—O4	110.0	C20—C21—O6	111.4 (3)
H8B—C8—C9	110.0	H21—C21—O6	124.3
H8B—C8—O4	110.0	C5—N—C6	118.48 (17)
C9—C8—O4	108.53 (19)	C5—N—H0	120.8
C8—C9—C10	121.9 (2)	C6—N—H0	120.8
C8—C9—C14	118.8 (2)	C4—O1—C5	120.18 (17)
C10—C9—C14	119.3 (2)	C7—O4—C8	116.75 (18)
C9—C10—H10	120.1	C18—O6—C21	106.2 (2)
C9—C10—C11	119.7 (3)
C15—C6—C7—O4	−91.0 (2)	C8—C9—C10—C11	−179.0 (3)
N—C6—C7—O4	146.13 (18)	C14—C9—C10—C11	1.5 (4)
C7—C6—C15—C16	172.11 (18)	C9—C10—C11—C12	−0.1 (5)
N—C6—C15—C16	−65.3 (2)	C10—C11—C12—C13	−1.7 (5)
C7—C6—N—C5	−77.3 (3)	C11—C12—C13—C14	1.9 (4)
C15—C6—N—C5	161.5 (2)	C8—C9—C14—C13	179.2 (2)
C6—C7—O4—C8	178.39 (19)	C10—C9—C14—C13	−1.3 (4)
C9—C8—O4—C7	178.54 (19)	C12—C13—C14—C9	−0.5 (4)
O4—C8—C9—C10	15.3 (3)	C15—C16—C17—O5	−16.8 (3)
O4—C8—C9—C14	−165.2 (2)	O5—C17—C18—C19	169.3 (3)
C6—C15—C16—C17	−179.35 (18)	O5—C17—C18—O6	−7.1 (3)
C15—C16—C17—C18	163.45 (19)	C17—C18—C19—C20	−176.4 (2)
C16—C17—C18—C19	−10.9 (4)	O6—C18—C19—C20	0.1 (3)
C16—C17—C18—O6	172.68 (18)	C18—C19—C20—C21	−0.3 (3)
O1—C5—N—C6	173.1 (2)	C19—C20—C21—O6	0.5 (4)
N—C5—O1—C4	177.16 (19)	O2—C5—N—C6	−8.3 (4)
C1—C4—O1—C5	178.8 (2)	O2—C5—O1—C4	−1.3 (4)
C2—C4—O1—C5	−63.7 (3)	O3—C7—O4—C8	−0.6 (3)
C3—C4—O1—C5	61.2 (3)	C20—C21—O6—C18	−0.4 (3)
N—C6—C7—O3	−34.9 (3)	C17—C18—O6—C21	177.3 (2)
C15—C6—C7—O3	87.9 (3)	C19—C18—O6—C21	0.2 (3)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N—H0···O2^i	0.88	2.20	3.032 (3)	158

Symmetry code: (i) x+1, y, z.