2-(6-Bromo­benzo[d]thia­zol-2-yl)-5,5-di­methyl­thia­zol-4(5H)-one

Würfel, H.; Görls, H.; Weiss, D.; Beckert, R.

doi:10.1107/S1600536813031334

organic compounds

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ISSN: 2056-9890

Volume 69| Part 12| December 2013| Page o1821

doi:10.1107/S1600536813031334

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2-(6-Bromobenzo[d]thiazol-2-yl)-5,5-dimethylthiazol-4(5H)-one

Hendryk Würfel,^a Helmar Görls,^b Dieter Weiss ^a and Rainer Beckert ^a ^*

^aInstitut für Organische Chemie und Makromolekulare Chemie, Universität Jena, Humboldtstr. 10, 07743 Jena, Germany, and ^bInstitut für Anorganische und Analytische Chemie, Friedrich-Schiller-Universität, Jena, Humboldt-Str. 8, 07743 Jena, Germany
^*Correspondence e-mail: c6bera@rz.uni-jena.de

(Received 4 November 2013; accepted 15 November 2013; online 23 November 2013)

The title compound, C₁₂H₉BrN₂OS₂, was obtained by reacting 6-bromobenzo[d]thiazole-2-carbonitrile in iso-propanol with ethyl 2-mercapto-2-methylpropanoate at reflux temperature for several hours. The resulting dimethyloxyluciferin derivative shows partial double-bond character of the carbon–carbon bond between the two heterocyclic moieties [C—C = 1.461 (3) Å]. This double bond restricts rotation around this C—C axis, therefore leading to an almost planar molecular structure [N—C—C—S torsion angle = 9.7 (3)°]. The five-membered thiazoline ring is not completely planar as a result of the bulky S atom [C—S—C—C torsion angle = 5.17 (12)°].

CCDC reference: 972176

Related literature

For the chemi- and bioluminescence of firefly luciferin and related compounds, see: Jung et al. (1975 ); White et al. (1961 , 1979 ); Branchini et al. (2002 ). For structural modifications of firefly luciferin, see: Meroni et al. (2009 ); McCutcheon et al. (2012 ); Branchini et al. (2012 ); Würfel (2012 ). Luciferin and related structures are widely used in clinical and biochemical applications, see: Schäffer (1987a ,b ); Kricka (1988 ); Josel et al. (1994a ,b ); Shinde et al. (2006 ). For details of the synthetic procedure, see: Armarego & Chai (2009 ); Bardsley et al. (2009a ,b ); Würfel et al. (2012 ).

Experimental

Crystal data

C₁₂H₉BrN₂OS₂
M_r = 341.24
Monoclinic, P 2₁ /c
a = 12.8246 (3) Å
b = 11.9115 (3) Å
c = 8.5375 (2) Å
β = 99.735 (1)°
V = 1285.41 (5) Å³
Z = 4
Mo Kα radiation
μ = 3.51 mm⁻¹
T = 133 K
0.06 × 0.05 × 0.04 mm

Data collection

Nonius KappaCCD diffractometer
7856 measured reflections
2927 independent reflections
2676 reflections with I > 2σ(I)
R_int = 0.033

Refinement

R[F² > 2σ(F²)] = 0.025
wR(F²) = 0.065
S = 1.02
2927 reflections
165 parameters
H-atom parameters constrained
Δρ_max = 0.44 e Å⁻³
Δρ_min = −0.40 e Å⁻³

Data collection: COLLECT (Nonius, 1998 ); cell refinement: DENZO (Otwinowski & Minor 1997 ); data reduction: DENZO; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: XP in SHELXTL/PC (Sheldrick, 2008); software used to prepare material for publication: SHELXL97.

Supporting information

CCDC reference: 972176

Crystal structure: contains datablocks I, New_Global_Publ_Block. DOI: 10.1107/S1600536813031334/im2444sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536813031334/im2444Isup2.hkl

Supporting information file. DOI: 10.1107/S1600536813031334/im2444Isup3.cml

checkCIF report

Comment top

Heterocycles are widely used in nature for a great variety of purposes. One of the most interesting ones is bioluminescence which is defined as the chemically stimulated emission of light by living organisms. One prominent example of a bioluminescent organism is the firefly (Photinus pyralis), which employs the benzothiazole containing Luciferin for light emission (White et al., 1961). One known inhibitor for this Luciferin-Luciferase reaction is the structurally close related dimethyloxyluciferin (Meroni et al., 2009). This compound also shows a bright red fluorescence in the visible spectrum in the deprotonated state (Branchini et al., 2002). Therefore investigations where conducted in our group focusing on modifications of the benzo[d]thiazol moiety of dimethyloxyluciferin (Würfel, 2012).

The title compound was synthesized by condensation of 6-bromobenzo[d]thiazole-2-carbonitrile with 2-mercapto-2-methylpropanoate. The Br—C bond length of 1.898 (2) Å (Br1—C4) is typical for a bromine atom bonded to an aromatic ring. The substituted benzo[d]-thiazol moiety builds up a planar structure, whereas the thiazoline ring is not exactly planar because of one sp³ carbon atom (C10). Since sp³ carbon atoms prefer smaller bond angles than sp² carbons, C10 is pushed out of the thiazoline plane. The C—C bond, connecting the heterocyclic moieties shows a partial double bond character (C1—C8, 1.461 (3) Å). The sulfur atoms S1 and S2 are arranged trans in the crystal, thus providing the maximal distance from each other (4.3686 (7) Å). Despite of the double bond character of C1—C8 the heterocyclic moieties are not exactly coplanar with respect to each other. The torsion angles N1—C1—C8—S2 show a deviation of -9.7 (3)°.

Related literature top

For the chemi- and bioluminescence of firefly luciferin and related compounds, see: Jung et al. (1975); White et al. (1961, 1979); Branchini et al. (2002). For structural modifications of firefly luciferin, see: Meroni et al. (2009); McCutcheon et al. (2012); Branchini et al. (2012); Würfel (2012). Luciferin and related structures are widely used in clinical and biochemical applications, see: Schäffer (1987a,b); Kricka (1988); Josel et al. (1994a,b); Shinde et al. (2006). For details of the synthetic procedure, see: Armarego & Chai (2009); Bardsley et al. (2009a,b); Würfel et al. (2012).

Experimental top

All chemicals were synthesized according to given literature or purchased from commercial sources. All solvents were purified and dried according to Armarego & Chai (2009). 3.46 g (14.5 mmol) 6-bromobenzo[d]thiazole-2-carbonitrile, 2.5 ml (approx. 17.4 mmol) ethyl 2-mercapto-2-methylpropanoate and 4.8 ml (34.8 mmol) triethylamine were refluxed in 20 ml of iso-propanol for 6 h. The product was recrystallized from ethanol yielding 70% (3.46 g, 10.1 mmol) pale yellow crystals. 6-Bromobenzo[d]thiazole-2-carbonitrile was prepared analog to Würfel et al. (2012). Ethyl 2-mercapto-2-methylpropanoate was prepared according to Bardsley et al. (2009a,b). Yellow single crystals of the title compound were obtained by dissolving the compound in ethanol at reflux temperature and after cooling to r. t. the closed vessel was left alone for several days. Elemental analysis calculated for C₁₂H₉BrN₂OS₂: C 42.24, H 2.66, Br 23.42, N 8.21, S 18.79; found: C 42.12, H 2.63, Br 23.51, N 8.11, S 19.00.

Computing details top

Data collection: COLLECT (Nonius, 1998); cell refinement: DENZO (Otwinowski & Minor 1997); data reduction: DENZO (Otwinowski & Minor 1997); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: XP in SHELXTL/PC (Sheldrick, 2008); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures top

Fig. 1. Molecular structure and numbering scheme of the title compound 1 showing displacement ellipsoids at the 40% probability level.

2-(6-Bromobenzo[d]thiazol-2-yl)-5,5-dimethylthiazol-4(5H)-one top

Crystal data top

C₁₂H₉BrN₂OS₂	F(000) = 680
M_r = 341.24	D_x = 1.763 Mg m⁻³
Monoclinic, P2₁/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 7856 reflections
a = 12.8246 (3) Å	θ = 2.4–27.5°
b = 11.9115 (3) Å	µ = 3.51 mm⁻¹
c = 8.5375 (2) Å	T = 133 K
β = 99.735 (1)°	Prism, colourless
V = 1285.41 (5) Å³	0.06 × 0.05 × 0.04 mm
Z = 4

Data collection top

Nonius KappaCCD diffractometer	2676 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	R_int = 0.033
Graphite monochromator	θ_max = 27.5°, θ_min = 2.4°
phi– + ω–scan	h = −16→16
7856 measured reflections	k = −15→15
2927 independent reflections	l = −11→11

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.025	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.065	H-atom parameters constrained
S = 1.02	w = 1/[σ²(F_o²) + (0.0282P)² + 1.1743P] where P = (F_o² + 2F_c²)/3
2927 reflections	(Δ/σ)_max = 0.001
165 parameters	Δρ_max = 0.44 e Å⁻³
0 restraints	Δρ_min = −0.40 e Å⁻³

Crystal data top

C₁₂H₉BrN₂OS₂	V = 1285.41 (5) Å³
M_r = 341.24	Z = 4
Monoclinic, P2₁/c	Mo Kα radiation
a = 12.8246 (3) Å	µ = 3.51 mm⁻¹
b = 11.9115 (3) Å	T = 133 K
c = 8.5375 (2) Å	0.06 × 0.05 × 0.04 mm
β = 99.735 (1)°

Data collection top

Nonius KappaCCD diffractometer	2676 reflections with I > 2σ(I)
7856 measured reflections	R_int = 0.033
2927 independent reflections

Refinement top

R[F² > 2σ(F²)] = 0.025	0 restraints
wR(F²) = 0.065	H-atom parameters constrained
S = 1.02	Δρ_max = 0.44 e Å⁻³
2927 reflections	Δρ_min = −0.40 e Å⁻³
165 parameters

Special details top

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 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The threshold expression of F² > σ(F²) is used only for calculating R-factors(gt) 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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
Br1	0.858415 (15)	0.276647 (17)	−0.06700 (2)	0.02385 (8)
S1	0.46626 (4)	0.21606 (4)	0.14052 (6)	0.01968 (11)
S2	0.26944 (4)	0.47143 (4)	0.31410 (6)	0.02169 (12)
O1	0.11449 (13)	0.20363 (13)	0.3753 (2)	0.0295 (4)
N1	0.48242 (12)	0.42814 (14)	0.21789 (19)	0.0197 (3)
N2	0.26810 (13)	0.25109 (15)	0.2854 (2)	0.0206 (3)
C1	0.42214 (15)	0.34012 (16)	0.2154 (2)	0.0190 (4)
C2	0.57634 (15)	0.28879 (16)	0.1035 (2)	0.0180 (4)
C3	0.66043 (15)	0.24949 (16)	0.0334 (2)	0.0188 (4)
H3A	0.6623	0.1748	−0.0049	0.023*
C4	0.74046 (15)	0.32508 (17)	0.0230 (2)	0.0188 (4)
C5	0.73963 (15)	0.43642 (17)	0.0770 (2)	0.0202 (4)
H5A	0.7973	0.4850	0.0691	0.024*
C6	0.65474 (15)	0.47491 (17)	0.1416 (2)	0.0208 (4)
H6A	0.6525	0.5505	0.1765	0.025*
C7	0.57210 (15)	0.40109 (16)	0.1549 (2)	0.0188 (4)
C8	0.32045 (15)	0.34245 (16)	0.2709 (2)	0.0189 (4)
C9	0.17367 (16)	0.27547 (16)	0.3418 (2)	0.0211 (4)
C10	0.14997 (15)	0.40174 (16)	0.3551 (2)	0.0195 (4)
C11	0.05518 (16)	0.43242 (19)	0.2281 (2)	0.0250 (4)
H11B	−0.0072	0.3904	0.2471	0.037*
H11C	0.0708	0.4134	0.1228	0.037*
H11D	0.0412	0.5131	0.2330	0.037*
C12	0.13018 (16)	0.42953 (18)	0.5223 (2)	0.0231 (4)
H12B	0.0677	0.3886	0.5433	0.035*
H12C	0.1183	0.5104	0.5307	0.035*
H12D	0.1919	0.4073	0.6002	0.035*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Br1	0.02181 (11)	0.02233 (12)	0.02884 (12)	0.00282 (7)	0.00841 (8)	−0.00194 (8)
S1	0.0206 (2)	0.0135 (2)	0.0256 (2)	−0.00276 (17)	0.00599 (19)	−0.00213 (18)
S2	0.0223 (2)	0.0131 (2)	0.0311 (3)	−0.00125 (17)	0.00843 (19)	−0.00089 (19)
O1	0.0320 (8)	0.0187 (7)	0.0420 (9)	−0.0057 (6)	0.0182 (7)	−0.0017 (7)
N1	0.0204 (8)	0.0157 (8)	0.0237 (8)	−0.0015 (6)	0.0059 (6)	−0.0001 (6)
N2	0.0204 (8)	0.0160 (8)	0.0263 (8)	−0.0018 (6)	0.0062 (7)	−0.0031 (7)
C1	0.0208 (9)	0.0163 (9)	0.0196 (9)	0.0010 (7)	0.0024 (7)	−0.0003 (7)
C2	0.0200 (9)	0.0158 (9)	0.0177 (9)	−0.0029 (7)	0.0019 (7)	0.0015 (7)
C3	0.0218 (9)	0.0138 (9)	0.0204 (9)	0.0018 (7)	0.0023 (7)	−0.0015 (8)
C4	0.0183 (8)	0.0198 (9)	0.0187 (9)	0.0023 (7)	0.0043 (7)	0.0016 (8)
C5	0.0212 (9)	0.0175 (9)	0.0220 (9)	−0.0030 (7)	0.0035 (7)	0.0009 (7)
C6	0.0224 (9)	0.0152 (9)	0.0258 (10)	−0.0004 (7)	0.0064 (8)	−0.0014 (8)
C7	0.0203 (9)	0.0157 (9)	0.0202 (9)	0.0006 (7)	0.0026 (7)	0.0007 (7)
C8	0.0216 (9)	0.0139 (9)	0.0209 (9)	0.0001 (7)	0.0024 (7)	−0.0003 (7)
C9	0.0231 (9)	0.0180 (10)	0.0229 (10)	−0.0001 (7)	0.0058 (8)	−0.0019 (8)
C10	0.0204 (9)	0.0158 (9)	0.0235 (9)	−0.0007 (7)	0.0067 (7)	−0.0001 (7)
C11	0.0232 (9)	0.0288 (11)	0.0226 (10)	0.0006 (8)	0.0031 (8)	0.0017 (8)
C12	0.0255 (10)	0.0225 (10)	0.0221 (10)	0.0031 (8)	0.0064 (8)	−0.0012 (8)

Geometric parameters (Å, º) top

Br1—C4	1.8985 (19)	C3—H3A	0.9500
S1—C2	1.730 (2)	C4—C5	1.405 (3)
S1—C1	1.742 (2)	C5—C6	1.379 (3)
S1—S2	4.3686 (7)	C5—H5A	0.9500
S2—C8	1.734 (2)	C6—C7	1.396 (3)
S2—C10	1.8276 (19)	C6—H6A	0.9500
O1—C9	1.210 (3)	C9—C10	1.542 (3)
N1—C1	1.301 (3)	C10—C12	1.528 (3)
N1—C7	1.387 (2)	C10—C11	1.530 (3)
N2—C8	1.296 (3)	C11—H11B	0.9800
N2—C9	1.407 (3)	C11—H11C	0.9800
C1—C8	1.461 (3)	C11—H11D	0.9800
C2—C3	1.399 (3)	C12—H12B	0.9800
C2—C7	1.412 (3)	C12—H12C	0.9800
C3—C4	1.379 (3)	C12—H12D	0.9800

C2—S1—C1	88.17 (9)	N1—C7—C2	114.75 (17)
C2—S1—S2	104.45 (7)	C6—C7—C2	120.10 (18)
C1—S1—S2	16.82 (6)	N2—C8—C1	121.36 (18)
C8—S2—C10	89.82 (9)	N2—C8—S2	120.25 (15)
C8—S2—S1	18.27 (7)	C1—C8—S2	118.38 (15)
C10—S2—S1	107.45 (6)	O1—C9—N2	123.07 (18)
C1—N1—C7	109.63 (17)	O1—C9—C10	122.21 (19)
C8—N2—C9	110.44 (17)	N2—C9—C10	114.71 (17)
N1—C1—C8	122.68 (18)	C12—C10—C11	111.89 (16)
N1—C1—S1	117.44 (15)	C12—C10—C9	110.22 (17)
C8—C1—S1	119.88 (15)	C11—C10—C9	108.90 (17)
C3—C2—C7	121.53 (17)	C12—C10—S2	110.94 (14)
C3—C2—S1	128.47 (15)	C11—C10—S2	110.32 (14)
C7—C2—S1	109.99 (15)	C9—C10—S2	104.29 (13)
C4—C3—C2	116.41 (18)	C10—C11—H11B	109.5
C4—C3—H3A	121.8	C10—C11—H11C	109.5
C2—C3—H3A	121.8	H11B—C11—H11C	109.5
C3—C4—C5	123.22 (18)	C10—C11—H11D	109.5
C3—C4—Br1	118.70 (15)	H11B—C11—H11D	109.5
C5—C4—Br1	118.07 (15)	H11C—C11—H11D	109.5
C6—C5—C4	119.70 (18)	C10—C12—H12B	109.5
C6—C5—H5A	120.2	C10—C12—H12C	109.5
C4—C5—H5A	120.2	H12B—C12—H12C	109.5
C5—C6—C7	118.98 (18)	C10—C12—H12D	109.5
C5—C6—H6A	120.5	H12B—C12—H12D	109.5
C7—C6—H6A	120.5	H12C—C12—H12D	109.5
N1—C7—C6	125.15 (18)

C2—S1—S2—C8	−164.7 (2)	C3—C2—C7—C6	−2.3 (3)
C1—S1—S2—C8	−149.8 (3)	S1—C2—C7—C6	177.93 (15)
C2—S1—S2—C10	179.56 (9)	C9—N2—C8—C1	179.51 (17)
C1—S1—S2—C10	−165.6 (2)	C9—N2—C8—S2	−1.7 (2)
C7—N1—C1—C8	−178.67 (17)	N1—C1—C8—N2	−171.43 (19)
C7—N1—C1—S1	0.8 (2)	S1—C1—C8—N2	9.2 (3)
C2—S1—C1—N1	−1.39 (16)	N1—C1—C8—S2	9.7 (3)
S2—S1—C1—N1	−167.0 (3)	S1—C1—C8—S2	−169.70 (11)
C2—S1—C1—C8	178.06 (16)	C10—S2—C8—N2	−2.53 (17)
S2—S1—C1—C8	12.46 (13)	S1—S2—C8—N2	−167.5 (3)
C1—S1—C2—C3	−178.28 (19)	C10—S2—C8—C1	176.35 (16)
S2—S1—C2—C3	−174.01 (16)	S1—S2—C8—C1	11.38 (12)
C1—S1—C2—C7	1.52 (15)	C8—N2—C9—O1	−174.9 (2)
S2—S1—C2—C7	5.78 (14)	C8—N2—C9—C10	6.1 (2)
C7—C2—C3—C4	2.4 (3)	O1—C9—C10—C12	54.4 (3)
S1—C2—C3—C4	−177.87 (15)	N2—C9—C10—C12	−126.62 (18)
C2—C3—C4—C5	−0.7 (3)	O1—C9—C10—C11	−68.7 (3)
C2—C3—C4—Br1	178.80 (14)	N2—C9—C10—C11	110.29 (19)
C3—C4—C5—C6	−1.2 (3)	O1—C9—C10—S2	173.56 (18)
Br1—C4—C5—C6	179.35 (15)	N2—C9—C10—S2	−7.5 (2)
C4—C5—C6—C7	1.3 (3)	C8—S2—C10—C12	123.84 (15)
C1—N1—C7—C6	−178.89 (19)	S1—S2—C10—C12	128.72 (12)
C1—N1—C7—C2	0.5 (2)	C8—S2—C10—C11	−111.60 (15)
C5—C6—C7—N1	179.72 (18)	S1—S2—C10—C11	−106.71 (13)
C5—C6—C7—C2	0.3 (3)	C8—S2—C10—C9	5.19 (14)
C3—C2—C7—N1	178.30 (17)	S1—S2—C10—C9	10.08 (14)
S1—C2—C7—N1	−1.5 (2)

Experimental details

Crystal data
Chemical formula	C₁₂H₉BrN₂OS₂
M_r	341.24
Crystal system, space group	Monoclinic, P2₁/c
Temperature (K)	133
a, b, c (Å)	12.8246 (3), 11.9115 (3), 8.5375 (2)
β (°)	99.735 (1)
V (Å³)	1285.41 (5)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	3.51
Crystal size (mm)	0.06 × 0.05 × 0.04

Data collection
Diffractometer	Nonius KappaCCD diffractometer
Absorption correction	–
No. of measured, independent and observed [I > 2σ(I)] reflections	7856, 2927, 2676
R_int	0.033
(sin θ/λ)_max (Å⁻¹)	0.649

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.025, 0.065, 1.02
No. of reflections	2927
No. of parameters	165
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.44, −0.40

Computer programs: COLLECT (Nonius, 1998), DENZO (Otwinowski & Minor 1997), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), XP in SHELXTL/PC (Sheldrick, 2008).

Acknowledgements

The authors thank Roche Diagnostics GmbH, Penzberg, for financial support.

References

Armarego, W. L. & Chai, C. L. (2009). Purification of Laboratory Chemicals, 6th ed. Amsterdam, Boston, Heidelberg, London, New York, Oxford, Paris, San Diego, San Francisco, Singapore, Sydney, Tokyo: Elsevier. Google Scholar
Bardsley, K., Agyemang, D. O. & Pei, T. (2009a). US patent US20090232747A1. Google Scholar
Bardsley, K., Agyemang, D. O. & Pei, T. (2009b). Chem. Abstr. 151, 366000. Google Scholar
Branchini, B. R., Murtiashaw, M. H., Magyar, R. A., Portier, N. C., Ruggiero, M. C. & Stroh, J. G. (2002). J. Am. Chem. Soc. 124, 2112–2113. Web of Science CrossRef PubMed CAS Google Scholar
Branchini, B. R., Woodroofe, C. C., Meisenheimer, P. L., Klaubert, D. H., Kovic, Y., Rosenberg, J. C., Behney, C. E. & Southworth, T. L. (2012). Biochemistry, 51, 9807–9813. Web of Science PubMed Google Scholar
Josel, H.-P., Herrmann, R., Klein, C. & Heindl, D. (1994a). German patent DE 4210759. Google Scholar
Josel, H.-P., Herrmann, R., Klein, C. & Heindl, D. (1994b). Chem. Abstr. 120, 164160. Google Scholar
Jung, J., Chin, C.-A. & Song, P.-S. (1975). J. Am. Chem. Soc. 97, 3949–3954. CrossRef Web of Science Google Scholar
Kricka, L. J. (1988). Anal. Biochem. 175, 14–21. CrossRef CAS PubMed Web of Science Google Scholar
McCutcheon, D. C., Paley, M. A., Steinhardt, R. C. & Prescher, J. A. (2012). J. Am. Chem. Soc. 134, 7604–7607. Web of Science CrossRef CAS PubMed Google Scholar
Meroni, G., Rajabi, M. & Santaniello, E. (2009). Arkivoc, pp. 265–288. CrossRef Google Scholar
Nonius (1998). COLLECT. Nonius BV, Delft, The Netherlands. Google Scholar
Otwinowski, Z. & Minor, W. (1997). Methods in Enzymology, Vol. 276, Macromolecular Crystallography, Part A, edited by Carter, C. W. Jr & Sweet, R. M., pp. 307–326. New York: Academic Press. Google Scholar
Schäffer, J. M. (1987a). US patent US 4665022. Google Scholar
Schäffer, J. M. (1987b). Chem. Abstr.107, 55320. Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Shinde, R., Perkins, J. & Contag, C. H. (2006). Biochemistry, 45, 11103–11112. Web of Science CrossRef PubMed CAS Google Scholar
White, E. H., Capra, F. M., Field, G. F. & McElroy, W. D. (1961). J. Am. Chem. Soc. 83, 2402–2403. CrossRef CAS Web of Science Google Scholar
White, E. H., Steinmetz, M. G., Miano, J. D., Wildes, P. D. & Morland, R. (1979). J. Am. Chem. Soc. 101, 3199–3208. Google Scholar
Würfel, H. (2012). PhD thesis, Friedrich-Schiller-University Jena, Germany. Google Scholar
Würfel, H., Weiss, D., Beckert, R. & Güther, A. (2012). J. Sulfur Chem. 33, 9–16. Google Scholar