Nitrogen chirality via the sterical veto of N inversion

Article abstract of DOI:10.1070/MC2003v013n03ABEH001751

Novel cyclic hydrazines 4-8 with sterically hindered (4, 6, 7) or arrested (5, 8) nitrogen inversion were synthesised; pyrazolydine 5 was separated into enantiomers by chiral chromatography; the crystal structures of salts 5a and 5b were studied by X-ray

Full text of DOI:10.1070/MC2003v013n03ABEH001751

,
2003, 13(3), 136–139
Nitrogen chirality via the sterical veto of N inversion†
a
b
c
a
d
Sergey V. Usachev, Grygorii A. Nikiforov, Yurii A. Strelenko, Ivan I. Chervin, Konstantin A. Lyssenko and
a
Remir G. Kostyanovsky*
a
N. N. Semenov Institute of Chemical Physics, Russian Academy of Sciences, 119991 Moscow, Russian Federation.
Fax: +7 095 938 2156; e-mail: kost@chph.ras.ru
b
N. M. Emanuel Institute of Biochemical Physics, Russian Academy of Sciences, 119991 Moscow, Russian Federation.
Fax: +7 095 137 4101; e-mail: komissarova@polymer.chph.ras.ru
c
N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 119991 Moscow, Russian Federation.
Fax: +7 095 135 5328; e-mail: strel@ioc.ac.ru
d
A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, 119991 Moscow, Russian Federation.
Fax: +7 095 135 5085; e-mail: kostya@xrlab.ineos.ac.ru
1
0.1070/MC2003v013n03ABEH001751
Novel cyclic hydrazines 4–8 with sterically hindered (4, 6, 7) or arrested (5, 8) nitrogen inversion were synthesised; pyrazolydine
5
was separated into enantiomers by chiral chromatography; the crystal structures of salts 5a and 5b were studied by X-ray
diffraction analysis.
The synthesis of 1,2-dialkyl-substituted five-membered cyclic
b,b'
1
hydrazines was reported in our previous publication. Unlike
(a)
2
3
,4-dialkyl-1,3,4-oxadiazolines, these hydrazines are highly
a,a'
c,c'
chemically stable; they form stable salts with acids and iodine
methylates. In a case of 3,4-di-tert-butyl-1,3,4-oxadiazolidine,
nitrogen inversion occurs by a dissociative mechanism with
3
O–CH2 bond cleavage, whereas the activation parameters
¹
–1
of 1,2-diisopropylpyrazolidine inversion (∆G = 67.7 kJ mol ,
¹
–1
¹
–1
–1
∆
H = 61.1 kJ mol , ∆S = –22.2 J K mol ) testify to a pyra-
midal character of the process. On the basis of a comparative
1
analysis of inversion barriers, we suggested a more than two-
Hb
4
3
i
5
ii
43%
3
+ CH =CHCHO
Ha
2
1
2
8
5%
N
N
But
But
But
4
(b)
2
N
H
c'
Ha
Hb'
4
HX
+
· H X–
5
5
3.2
3.1
3.0
2.9
d/ppm
2.8 2.1
2.0
1.9
3
Hb
N
1
Ha' Hc
But
Figure 1 1H NMR spectra of 5: (a) experimental (500 MHz, in CDCl at
3
5
20 °C) and (b) calculated using CALM.
Scheme 2 Reagents and conditions: i, 2 h at 20 °C; ii, HCO H in 1,4-di-
2
–
–
Reaction of 1,2-di-tert-butylhydrazine 3 with acrolein gives
oxane at 90–95 °C; X = HSO (5a) and TsO (5b).
4
‡
pyrazoline 4; its reduction with 98% HCO H results in 1,2-di-
2
tert-butylpyrazolidine 5 (Scheme 2).
fold increase in the inversion barrier when transferring from
The structures of compounds 4 and 5 were confirmed by
1
,2-diisopropylpyrazolidine to a 1,2-di-tert-butyl analogue, that
§
NMR data. In the case of pyrazoline 4, a flat screen for N(1)
would provide an opportunity for obtaining the compound in an
optically active form under normal conditions.
This work is aimed at the experimental evidence of the above
assumption.
inversion is created due to the flattening of the enamine N(2)
atom. Thus, its inversion is hindered in the NMR time scale at
1
13
1
2
3
0 °C ( H NMR, d: 5-CH , ∆n 23 Hz. C NMR, d: 5-CH , ∆ J
2 2
2
.8 Hz), and the signal of 5-C dd at 55.68 ppm in [ H ]toluene
8
Initial di-tert-butylhydrazine 3 was prepared without isolation
is not transformed (dd ® t) under heating up to 100 °C.
The NMR spectra of 1,2-di-tert-butylpyrazolidine 5 (Figure 1)
of rather labile intermediate 1,2-di-tert-butylthiadiaziridine
4
oxide 2 (Scheme 1); this resulted in an increase in the yield
are indicative of the C molecular symmetry and strongly hin-
4
2
of 3 up to 75% (cf. 56% ).
dered nitrogen inversion. The non-equivalence of geminal Ha
and H protons is observed, the signal of 3,5-C at 42 ppm dd
b
t
i
t
ii
with ∆ J 10 Hz is not transformed into a triplet in [ H ] toluene
1
2
2
Bu NH + 2 NEt3 + SO Cl2
(Bu NH) SO
8
2
2
2
2
7
1%
at 100 °C.
1
O
N
O
‡
§
5
This method was used in reduction of enamines.
1H and 13C NMR spectra were measured on Bruker DRX-500, WM-400
S
iii
5%
t
iv
96%
t
(
Bu NH) ·H SO
(Bu NH)2
2
2
4
7
and AM-300 spectrometers.
prepared in accordance with Scheme 1, 71% yield, mp 140–142 °C
N
But
But
3a
3
1
4
1
(
2
lit., mp 141–142 °C). H NMR (CDCl3 at 20 °C) d: 1.33 (s, 18H,
Bu ), 4.41 (s, 2H, NH).
2
t
Scheme 1 Reagents and conditions: i, 3 h at –5 °C; ii, NaH in hexane at
0 °C, then Bu OCl at –30 °C; iii, boiling in THF/H O 2 h at 65 °C; iv,
3a prepared in accordance with Scheme 1, 75% yield, mp 174–175 °C.
t
6
1
2
t
2
H NMR ([ H ]DMSO at 20 °C) d: 1.82 (s, 18H, 2Bu ), 3.48 (s, 4H,
6
KOH/H O.
9
2
–NH–NH– H SO ). Base 3, 96% yield, bp 134–137 °C (lit., bp 137–
2
4
1
t
1
38 °C). H NMR (CDCl at 20 °C) d: 1.01 (s, 18H, 2Bu ), 2.81 (s,
3
†
2H, 2NH).
Asymmetric nitrogen. Part 87, previous communication see ref. 1.
–
136 –

,
2003, 13(3), 136–139
Attempts to separate enantiomers 5 by means of diastereo-
meric salts with (1S)-(+)-10-camphorsulfonic acid have failed.
Therefore, HPLC was used for resolution on microcrystalline
¶
triacetyl cellulose; however, it was not efficient. Complete sepa-
7
ration of 5 was detected by GLC on a Chirasil-β-Dex chiral
stationary phase, and narrow non-overlapped peaks of enantio-
1
2.55
13.05
4
prepared in accordance with Scheme 2 and separated by chromato-
2
0
1
graphy (SiO 40/60 µ. Eluent: CHCl ) 85% yield. n 1.5257. H NMR
2
3
D
2
t
t
(
[ H ]toluene at 20 °C) d: 1.05 (s, 9H, Bu -1), 1.12 (s, 9H, Bu -2), 3.42
8
2
3
4
(
ddd, 1H, H , J –15.2 Hz, J 2.81 Hz, J 1.58 Hz), 3.55 (ddd, 1H, H ,
J –15.2 Hz, J 2.77 Hz, J 1.47 Hz), 4.94 (ddd, 1H, 4-CH, J 5.34 Hz,
J 2.77 Hz, J 2.81 Hz), 5.95 (ddd, 1H, 3-CH, J 5.34 Hz, J 1.47 Hz,
J 1.58 Hz). C NMR ([ H ]toluene at 20 °C) d: 27.63 (q, Me C,
25.5 Hz), 28.23 (q, Me C, J 125.5 Hz), 54.68 (dddd, CH , J 135.97
and 139.63 Hz, J ~ J 7.6 Hz), 110.48 (dm, 4-C, J 169.9 Hz), 137.99
dm, 3-C, 177.6 Hz), 58.18 (s, CMe ), 60.14 (s, CMe ).
a
b
2
3
4
3
3
4
3
3
4
13
2
1
J
8
1
3
1
1
3
2
2
3
1
4
8
12
(
t/min
3
3
5
prepared in accordance with Scheme 2 and separated by chromato-
Figure 2 Separation of the enantiomers of 5 by GLC on Chirasil-β-Dex
column 25 m, i.d. 0.25 mm, H , 0.1 atm) at 110 °C.
1
graphy (SiO 40/60 µ. Eluent: CHCl ) 43% yield. H NMR (500 MHz,
CDCl at 20 °C) d: 1.12 (s, 18H, 2Bu ), 1.98 (m, 2H, H H ), 2.87 (m,
H, H H ), 3.18 (m, 2H, H H ), J = J = –12.37 Hz, J –11.93 Hz,
2
3
(
t
2
3
c
c'
2
2
2
2
J
=
b b' a a' ab a'b' cc'
3
3
3
3
3
3
3
mers, which are configurationally stable even at 110 °C, were
= J = 3.84 Hz, J = J = 7.62 Hz, J = J = 10.09 Hz, J
=
ac
a'c'
bc
b'c'
a'c
ac'
13
b'c
3Jbc' = 10.21 Hz, J = 0.45 Hz, J = 0.75 Hz. C NMR (125 MHz,
4
4
observed (Figure 2).
bb'
aa'
CDCl3 at 20 °C) d: 28.32 (Me C), 29.49 (4-CH ), 47.44 (3,5-CH ),
3
2
2
1
13
2
5
7.67 (CMe ). C NMR (100 MHz, [ H ]toluene at 20 °C) d: 29.40 (q,
3
8
1
1
Me C, J 124.7 Hz), 30.57 (t, 4-CH , J 129.2 Hz), 48.57 (dd, 3,5-CH ,
3
2
2
1
1
J 131.7 Hz, J 140.8 Hz), 58.73 (s, CMe ). Found (%): C, 71.37; H,
0
3
1
3.43; N, 15.50. Calc. for C H N (%): C, 71.68; H, 13.12; N, 15.20.
11 24 2
1
2
Hydrogen sulfate 5a: mp 131–132 °C (acetone). H NMR ([ H ]DMSO
6
+
–1
–2
at 20 °C) d: 1.19 (br. s, 9H, Me CN-2), 1.32 (br. s, 9H, Me CN -1), 2.21
3
3
(
1
br. s, 2H, H H ), 3.11 (br. s, 1H, H ), 3.51 (br. s, 1H, H ), 3.61 (br. s,
b' a' c' c
+
H, H ), 3.82 (br. s, 1H, H ), 9.30 (br. s, 1H, HN ).
p-Toluenesulfonate 5b: mp 145–146 °C (acetone). H NMR (CDCl at
a
b
'
1
3
+
2
0 °C) d: 1.27 (s, 9H, Me CN-1), 1.42 (s, 9H, Me CN -2), 2.28 (m, 2H,
3
3
–3
CH -4, ∆n 45.6 Hz), 2.31 (s, 3H, MeC H ), 3.33 (m, 2H, CH -N-1,
2
6
4
2
2
3
3
3
AB spectrum, ∆n 142.6 Hz, J –12.7 Hz, J = J = 9.1 Hz, J 9.8 Hz,
by
12.8 Hz), 7.12 and 7.74 (2d, 2×2H, C H , J 8.0 Hz), 10.17 (br. s,
H, HN ).
ax
ay
bx
3
+
2
J
3.5 Hz), 3.88 (m, 2H, CH -N -2, AB spectrum, ∆n 220.0 Hz, J
2
–4
3
–
1
6
4
+
–5
6
prepared in accordance with Scheme 4 and separated by chromato-
0
.00030
0.00032
0.00034
0.00036
0.00038
1
graphy (SiO 40/60 µ. Eluent: CHCl ) 56% yield. H NMR (400 MHz,
H ]toluene at 20 °C) d: 0.74 (d, 6H, 2Me-A, J 6.4 Hz), 0.85 (d, 6H,
Me-B, J 6.4 Hz), 2.50 (hept, 2H, 2HCN), 2.82 (m, 4H, 2,5-CH , AB
spectrum, ∆n 100.0 Hz, J –19.0 Hz). C NMR { H} ([ H ]toluene at
0 °C) d: 19.72 (Me), 23.28 (CHN), 55.52 (CH N), 217.24 (CO). Found
2
3
2
3
1/RT
[
8
3
2
2
Figure 3 Kinetics of N atom inversion in 6 (R-factor: 0.99924; standard
deviation: 0.0542).
2
13
1
2
8
2
2
(
1
%): C, 63.18; H, 10.78; N, 16.11. Calc. for C H N O (%): C, 63.49; H,
0.66; N, 16.45.
9 18 2
The further increase of the configurational stability of pyrazo-
lidines is possible due to the elimination of 1,3-non-bonded
interactions, which destabilise the ground state. That is why
7
prepared in accordance with Scheme 4, 43% yield, bp 83–85 °C
1
3
(25 torr). H NMR (CDCl at 20 °C) d: 0.89 (d, 3H, Me-A, J 6.2 Hz),
3
3
3
1,2-diisopropylpyrazolidin-4-one 6 was synthesised (Scheme 3)
1
0
3
2
3
.94 (d, 3H, Me-B, J 6.2 Hz), 0.97 (d, 3H, Me-A', J 6.2 Hz), 1.00 (d,
H, Me-B', J 6.2 Hz), 1.15 (d, 3H, 5-Me, J 6.7 Hz), 1.65 (s, 3H, 3-Me),
.89 (hept, 1H, HCN-1, J 6.2 Hz), 3.22 (hept, 1H, HCN-2, J 6.2 Hz),
.64 (br. m, 1H, 5-H, J 6.7 Hz), 4.48 (br. s, 1H, 4-H).
3
3
1
using oxidation of 1,2-diisopropylpyrazolidin-4-ol under the
3
3
††
action of DMSO activated with (COCl)2 with higher yield
3
1
(
cf. 12% ).
8
prepared in accordance with Scheme 4, 80% yield, bp 88–90 °C
20
1
(
23 torr), n 1.4446. H NMR (CDCl at 20 °C) d: 0.99 (d, 6H, 2Me-A,
D
3
OH
N
O
3
3
3
J 6.35 Hz), 1.04 (d, 6H, 2Me-B, J 6.6 Hz), 1.10 (d, 6H, 3,5-Me, J
.5 Hz), 1.76 (t, 2H, H H , J 6.5 Hz), 2.78 (hept, 2H, HCMe , J 6.6 Hz),
.13 (qt, 2H, H H , J 6.5 Hz). C NMR ([ H ]benzene at 20 °C) d:
1.3 (qq, Me-A, J 124.8 Hz, J 4.5 Hz), 22.2 (qm, Me-B, J 124.8 Hz),
4.2 (qt, Me-C, J 124.9 Hz, J 9.0 Hz), 43.8 (t, 4-C, J 129.0 Hz), 56.3
dm, CHN, J 132.2 Hz, J 3.0 Hz), 57.8 (dqt, 3,5-C, J 133.5 Hz, J
.0 Hz).
Hb
Ha
Ha
Hb
3
3
6
3
2
2
(
4
b
b
'
2
i
3
13
2
a
1
a'
6
56%
3
1
N
N
N
1
3
1
Pri
Pri
Pri
Pri
1
2
1
2
6
1
Hydrochloride 8: mp 178–179 °C (acetone). H NMR (CDCl at 20 °C)
Scheme 3 Reagents and conditions: i, CH Cl , DMSO/(COCl) , Et N,
2 2 2 3
15 min at –60 °C.
3
3
d: 1.18 (d, 3H, A-MeCHN-1, J 6.5 Hz), 1.24 (d, 3H, B-MeCHN-1,
3
3
J 6.5 Hz), 1.26 (d, 3H, C-MeCHN-1, J 6.3 Hz), 1.38 (d, 3H, A-Me–
+
3
+
3
CHN -2, J 6.3 Hz), 1.38 (d, 3H, B-MeCHN -2, J 6.3 Hz), 1.51 (d, 3H,
C-MeCHN -2, J 6.8 Hz), 1.68 (dt, 1H, H , J –13.3 Hz, J 13.3 Hz, J
1
1
From the full line shape analysis in the H DNMR spectra,
the following activation parameters of the nitrogen inversion
+
3
2
3
3
b
2
3
3
1.4 Hz), 2.42 (dt, 1H, H , J –13.3 Hz, J 13.3 Hz, J 6.6 Hz), 3.60
qdd, 1H, H , J 6.3 Hz, J 13.3 Hz, J 6.6 Hz), 3.64 (hept, 1H, HCN-1,
J 6.5 Hz), 3.70 (hept, 1H, HCN -2, J 6.3 Hz), 3.97 (qdd, 1H, H , J
.6 Hz, J 6.8 Hz, J 11.4 Hz); 12.3 (br. s, 1H, HN -2 ).
Meso-form 8: H NMR [CDCl –C D (7:1) at 20 °C] d: 1.06 (d, 6H,
Me-A, J 6.5 Hz), 1.1 (d, 6H, 2CHMe-B, J 6.5 Hz), 1.24 (d, 6H, 3,5-Me,
J 6.5 Hz), 1.48 (dt, 1H, H , J –11.7 Hz, J 11.7 Hz), 1.89 (dt, 1H, H ,
J –11.7 Hz, 3J 6.5 Hz), 3.07 (hept, 2H, 2HCN, J 6.5 Hz), 3.1–3.4
¹
–1
b'
in pyrazolidine 6 were obtained: ∆G = 73.3±0.6 kJ mol at
3
3
3
(
a
¹
–1
¹
–1
–1
–1
2
5 °C, ∆H = 66.4±0.6 kJ mol , ∆S = –23.3±1.7 J K mol
3
+
3
3
a'
(
Figure 3). The real inversion barrier is about 5.6 kJ mol
3
3
+
6
1
1
higher than that for 1,2-di-tert-butylpyrazolidine.
3
6
6
3
3
To arrest completely nitrogen inversion, previously unknown
2
3
2
2
3
1,2-diisopropyl-3,5-dimethylpyrazolidine 8 (Scheme 4) was
b
b'
3
synthesised veto of N atoms inversion. Methyl propenyl ketone
1
(
¶
br. s, 2H, H H ).
a
a'
††
Enantiomers of the substituted diaziridines are well separated on this
This method was used for mild oxidation of alcohols to aldehydes and
phase.6
ketones.
8
–
137 –

,
2003, 13(3), 136–139
respectively, while in 5a, by the envelope with deviation of the
C(3) atom by 0.45 Å. The tert-butyl groups in all the structures
are in axial positions; the nonprotonated nitrogen atom is pyra-
midal with a deviation from its neighbours by ~0.47 Å (0.48 Å
in A). The main difference between the salts of 5 and A is
reflected in some lengthening of all bonds formed by the N(1)
atom. In particular, the N(1)–N(2) bond [1.485(2) and 1.479(3) Å]
in the salt of 5 is elongated by ~0.05 Å in comparison with A.
The analysis of the crystal packing in 5a and 5b demonstrated
that anions assemble molecules in double layers parallel to the
crystallographic plane ab by a number of C–H···O contacts
(H···O 2.33–2.55 Å, CHO 131–172°). In 5a salt within the layers
HSO4– anions are assembled into centrosymmetric dimers by the
O(3)
H(4O)
O(4)
O(1)
C(12)
O(2) S(1)
H(13A)
C(13)
C(10)
C(11)
H(1N)
N(1)
C(5)
N(2)
C(4)
C(3)
H(7C)
C(7)
C(9)
C(6)
C(8)
C(20)
C(17)
Figure 4 The general view of a close ion pair in the crystal of sulfate 5a.
Selected bond lengths (Å): N(1)–N(2) 1.479(3), N(1)–C(5) 1.538(4), N(1)–
C(6) 1.561(4), N(2)–C(3) 1.482(4), N(2)–C(10) 1.520(4), C(3)–C(4)
C(18)
C(16)
1
.531(5), C(4)–C(5) 1.507(5), S(1)–O(2) 1.429(2), S(1)–O(1) 1.446(2),
S(1)–O(3) 1.486(2), S(1)–O(4) 1.534(3); bond angles (º): N(2)–N(1)–C(5)
09.2(2), N(2)–N(1)–C(6) 111.5(2), C(5)–N(1)–C(6) 112.9(2), N(1)–N(2)–
C(19)
C(15)
1
C(14)
C(3) 103.8(2), N(1)–N(2)–C(10) 112.6(2), C(3)–N(2)–C(10) 114.9(2),
N(2)–C(3)–C(4) 107.7(2), C(5)–C(4)–C(3) 104.2(3), C(4)–C(5)–N(1)
C(11)
C(10)
O(2)
S(1)
C(12)
H(11C)
1
05.7(2), O(2)–S(1)–O(1) 113.7(2), O(2)–S(1)–O(3) 110.3(2), O(1)–S(1)–
O(3) 111.4(2), O(2)–S(1)–O(4) 106.6(2), O(1)–S(1)–O(4) 108.2(1), O(3)–
S(1)–O(4) 106.1(1). Hydrogen bond: N(1)–H(1)···O(1) [N(1)···O(1)
O(3)
C(13)
O(1)
H(13C)
H(1N)
2.853(1) Å, H(1)···O(1) 1.97 Å, N(1)H(1N)O(1) 155°].
C(4)
N(2)
C(3)
C(7)
C(5)
N(1)
was condensed with N,N'-diisopropylhydrazine to yield pyrazo-
H(9C)
C(9)
line 7, the reduction of which with 98% HCO H results in 8
2
C(6)
C(8)
(
according to NMR, it is a mixture of d,l/meso forms in a ratio
§
of ~5:1).
H
4
3
Me
O
5
Me 1
Figure 5 The general view of a close ion pair in the crystal of p-toluene-
sulfonate 5b. The selected bond lengths (Å): N(1)–N(2) 1.485(2), N(1)–
C(5) 1.535(2), N(1)–C(6) 1.556(2), N(2)–C(3) 1.490(2), N(2)–C(10)
i
i
+
(Pr NH)2
N
N
2
4
8%
Me
Me
A-Me
Me-B'
1
.515(2), C(3)–C(4) 1.535(2), C(4)–C(5) 1.514(2), S(1)–O(1) 1.471(1),
S(1)–O(2) 1.458(1), S(1)–O(3) 1.455(1), S(1)–C(14) 1.783(1); bond angles
°): N(2)–N(1)–C(5) 109.0(1), N(2)–N(1)–C(6) 111.8(1), C(5)–N(1)–C(6)
14.0(1), N(1)–N(2)–C(3) 104.1(1), N(1)–N(2)–C(10) 112.6(1), C(3)–
N(2)–C(10) 115.1(1), N(2)–C(3)–C(4) 108.6(1), C(5)–C(4)–C(3) 105.7(1),
C(4)–C(5)–N(1) 105.7(1), O(3)–S(1)–O(2) 113.22(7), O(3)–S(1)–O(1)
113.59(7), O(2)–S(1)–O(1) 112.35(7), O(3)–S(1)–C(14) 105.82(7), O(2)–
S(1)–C(14) 105.82(7), O(1)–S(1)–C(14) 105.14(7). Hydrogen bond N(1)–
H(1)···O(1) [N(1)···O(1) 2.862(1) Å, H(1)···O(1) 2.00 Å, N(1)H(1N)O(1)
159°].
B-Me
Me-A'
7
(
1
A-Me
Me-B
Me-C
1
H
N
b'
ii
Ha
4
3
5
8
0%
Ha'
Me-A
N
Hb
2
C-Me
B-Me
8
‡
‡
X-ray structure analysis. Crystals of sulfate 5a (C H N O S) at
1
1
26
2
4
Scheme 4 Reagents and conditions: i, n-pentane, 1 h at 4–6 °C; ii, HCO H
2
170 K are monoclinic, space group P2 /n: a = 10.550(4) Å, b =
=
dcalc = 1.307 g cm , m = 2.35 cm , F(000) = 616; crystals of p-toluene-
sulfonate 5b (C H N O S) at 110 K are monoclinic, space group P2 /c:
a = 8.088(3) Å, b = 8.767(4) Å, c = 27.865(8) Å, b = 93.749(14)°, V =
=
1
in 1,4-dioxane, 1 h at 60–65 °C.
3
11.511(4) Å, c = 11.951(4) Å, b = 98.645(8)°, V = 1434.9(9) Å , Z = 4,
–
3
–1
1
The H MNR data are indicative of the C molecular sym-
2
1
8
32
2
3
1
metry of 8. Apparently, the inversion of N atoms in 8 is impos-
sible due to strong steric hindrances in the epimeric form.
Thus, the nitrogen chirality via sterical veto of N inversion
became a preparative reality.
3
–3
–1
1972(1) Å , Z = 4, d = 1.201 g cm , m = 1.82 cm , F(000) = 776.
calc
Intensities of 8346 (5a) and 12879 (5b) reflections were measured on
a SMART 1000 CCD diffractometer at 110 K [ (MoKα) = 0.71072 Å,
l
Salts 5a and 5b were studied by X-ray diffraction analysis‡‡
for searching the conglomerates and defining the geometry of
molecules. We found that 5a and 5b are racemates, and they
exist in crystals in the form of close ion pairs due to the N–H···O
hydrogen bonds formed by the protonated nitrogen and the
oxygen of the anions and also due to the number of the C–H···O
contacts (Figures 4 and 5). Note that in spite of some dif-
ferences of anion nature the N(1)···O(1) distances, which char-
acterise the N–H···O bond strength, in 5a and 5b are equal.
Thus, probably, the N···O distance is controlled by steric (tert-
butyl groups) rather than electronic factors. The comparison of
the bond lengths and angles in 5a and 5b revealed that they are
close to the corresponding values in 3,4-di-tert-butyl-1,3,4-oxa-
diazolidine A,10 but the conformation of a five-membered ring
is more sensitive to the peculiarities of crystal packing. Thus, in
w-scan technique, 2q < 52º (5a) and 60° (5b)], 2705 (5b) and 5361 (5a)
independent reflections [Rint = 0.0250 (5b) and 0.0193(5a)] were used in
the further refinement. The structure was solved by a direct method and
2
refined by the full-matrix least-squares technique against F in the aniso-
tropic–isotropic approximation. The refinement converged to wR =
=
was calculated against F for 2305 observed reflections with I > 2s(I)]
for 5a and to wR = 0.1061 and GOF = 1.076 for all independent reflec-
tions [R = 0.0443 was calculated against F for 4301 observed reflections
with I > 2s(I)] for 5b. All calculations were performed using SHELXTL
2
0.1497 and GOF = 1.074 for all independent reflections [R = 0.0667
1
2
1
PLUS 5.0.
Atomic coordinates, bond lengths, bond angles and thermal param-
eters have been deposited at the Cambridge Crystallographic Data Centre
(CCDC). These data can be obtained free of charge via www.ccdc.cam.uk/
conts/retrieving.html (or from the CCDC, 12 Union Road, Cambridge
CB2 1EZ, UK; fax: +44 1223 336 033; or deposit@ccdc.cam.ac.uk).
Any request to the CCDC for data should quote the full literature citation
and CCDC reference numbers 212043 and 212044. For details, see ‘Notice
to Authors’, Mendeleev Commun., Issue 1, 2003.
5
b and A, the ring is characterised by the envelope conforma-
tion with the deviation of the N(2) atom by 0.385 and 0.388 Å,
–
138 –

,
2003, 13(3), 136–139
O(4)–H(4O)···O(3A) (–x, –y – 1, –z + 1) [O(4)···O(3A) 2.617(2) Å,
5
P. L. de Benneville and J. H. Macartney, J. Am. Chem. Soc., 1950, 72,
073.
M. Mintas, A. Mannschreck and L. Klasing, Tetrahedron, 1981, 37, 867.
V. Schurig, D. Schmalzing and M. Schleimer, Angew. Chem., Int. Ed.
Engl., 1991, 30, 987.
3
1
.79 Å, 165º] intermolecular H-bond.
6
7
We are grateful to D. A. Lenev for the GLC analysis of 1,2-di-
tert-butylpyrazolidine.
This work was supported by INTAS (grant no. 99-00157),
the Russian Academy of Sciences and the President of the
Russian Federation (grant ‘Scientific School’ no. 1060.2003.3).
8
9
K. Omura and D. Swern, Tetrahedron, 1978, 34, 1651.
F. D. Greene, J. E. Stowell and W. R. Bermark, J. Org. Chem., 1969,
34, 2254.
10 R. G. Kostyanovsky, G. K. Kadorkina, V. N. Voznesensky, I. I. Chervin,
M. Yu. Antipin, K. A. Lyssenko, E. V. Vorontzov, V. I. Bakhmutov and
P. Rademacher, Mendeleev Commun., 1996, 69.
References
1
S. V. Usachev, G. A. Nikiforov, Y. A. Strelenko, P. A. Belyakov, I. I.
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2
1
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3
4
R. G. Kostyanovsky, G. K. Kadorkina, V. R. Kostyanovsky, V. Schurig
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Received: 7th April 2003; Com. 03/2077
–
139 –