Synthesis of the first representatives of 3-ethynyldiaziridines

Article abstract of DOI:10.1070/MC2001v011n06ABEH001500

1,2-Dimethyl-3-(3,3-diethoxypropyn-1-yl)- and 1,2-dimethyl-3-(3-hydroxymethyl-3-methylbutyn-1-yl)diaziridines have been synthesised by the interaction of 4,4-diethoxybutyn-2-al and 4-hydroxymethyl-4-methylpentyn-2-al, respectively, with equimolar amounts of MeNH₂ and MeNHCl (or MeNHOSO₃H) at pH 9.5-10; the use of an excess of an amine in reactions with 4,4-diethoxybutyn-2-al resulted in a mixture of isomeric 5(3)-diethoxymethyl-1-methylpyrazoles and a mixture of Z/E isomers of 1-cyano3,3-diethoxy-2-methylaminoprop-1-enes.

Full text of DOI:10.1070/MC2001v011n06ABEH001500

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Synthesis of the first representatives of 3-ethynyldiaziridines
Nina N. Makhova,* Nailya G. Kamalova and Yurii A. Strelenko
N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 119991 Moscow, Russian Federation.
Fax: +7 095 135 5328; e-mail: mnn@ioc.ac.ru
10.1070/MC2001v011n06ABEH001500
1,2-Dimethyl-3-(3,3-diethoxypropyn-1-yl)- and 1,2-dimethyl-3-(3-hydroxymethyl-3-methylbutyn-1-yl)diaziridines have been
synthesised by the interaction of 4,4-diethoxybutyn-2-al and 4-hydroxymethyl-4-methylpentyn-2-al, respectively, with equimolar
amounts of MeNH2 and MeNHCl (or MeNHOSO3H) at pH 9.5–10; the use of an excess of an amine in reactions with 4,4-di-
ethoxybutyn-2-al resulted in a mixture of isomeric 5(3)-diethoxymethyl-1-methylpyrazoles and a mixture of Z/E isomers of 1-cyano-
3,3-diethoxy-2-methylaminoprop-1-enes.
A number of general methods for the synthesis of diaziridines
are known, for example, the reactions of Schiff bases with ami-
EtO
i
nating reagents1,2 or the interaction of primary aliphatic amines
with the products of condensation of a carbonyl compound and
an aminating reagent,3–5 in particular with hydroxylamine-O-
sulfonic acid.6 In recent years, new versatile approaches to the
construction of the diaziridine ring were developed. Alkyl deriv-
atives and condensed diaziridine-containing systems were pre-
pared in one step,7–10 in particular, by the reactions of carbonyl
compounds, primary aliphatic amines and aminating reagents in
water at controlled pH values7,8 and in organic solvents in the
presence of K2CO3.10 All of these methods were used for the
synthesis of only saturated derivatives of alkylaziridines. Deriva-
tives with unsaturated alkyl substituents directly at the diaziridine
ring were not described previously. Reactive unsaturated substi-
tuents will provide an opportunity to introduce additional chiral
fragments into diaziridine molecules, which are racemates,11–13
with the subsequent resolution into enantiomers. In addition,
such a kind of diaziridine derivatives is of interest as triazolyl-
diaziridine precursors.
C
C
CHO + H2NOSO3H
EtO
1a
iii
EtO
EtO
EtO
C
C
CN
C
C
CH NOSO3H
EtO
7
4
iv
ii
OEt
OEt
OEt
EtO
H
EtO
CN
H
H
EtO
C
C
H
N
MeHN
CN MeHN
N
6a
6b
5
Me
In this work, based on α-acetylenic aldehyde derivatives, we
synthesised the first diaziridines of this kind, which contained
an acetylene unit at the 3-position of the diaziridine ring. Readily
available 4,4-diethoxybutyn-2-al14 1a was studied in more
detail. It is well known that α-ethynyl carbonyl compounds can
add amines not only at the carbonyl group but also at the triple
bond to form enamines.15 However, by analogy with published
data,16 we expected that the presence of a bulky diethoxymethyl
group in aldehyde 1a will allow us to prevent this undesirable
reaction path.
Unfortunately, we found that diaziridine synthesis methods
with the use of an excess of an amine did not result in desired
diaziridines. In particular, we failed to prepare 1,2-dimethyl-3-
(3,3-diethoxypropyn-1-yl)diaziridine 3a by the reaction of Schiff
base 2 (synthesised as described previously16) with N-chloro-
methylamine in the presence of an excess of methylamine (or
triethylamine) according to methods1,2 (Scheme 1).
Scheme 2 Reagents and conditions: i, NH2OSO3H (equimol), H2O,
0–5 °C, 15–20 min; ii, MeNH2 (3 mol), H2O, –15–10 °C ® 20 °C, 1 h; iii,
NH2OSO3H (equimol), H2O, 0–5 °C, 10 min, 20% NaOH, then extraction
with diethyl ether; iv, MeNH2 (1 mol), MeOH–H2O, 18–20 °C, 15–20 min.
with a total yield of 65% and a ratio of 5:1 between the Z/E
isomers in place of expected 1-methyl-3-(3,3-diethoxypropyn-
1-yl)diaziridine 5. By analogy with published data,17 we believe
that Z-isomer 6a is predominant because a signal due to the
=CH unit in its 1H NMR spectrum is upfield shifted with
respect to an analogous signal of isomer 6b. The formation of
enaminonitriles 6a,b via 1-cyano-3,3-diethoxyprop-1-yne 7
followed by the addition of methylamine at the triple bond can
be represented as shown in Scheme 2. The same result was
obtained by the interaction of compound 7, which was prepared
according to ref. 18, with an excess of methylamine. It is likely
that the nitrile group in compound 7 results from the Beckmann
fragmentation of the CH=NOSO3H group in 4.
The reaction of aldoxime-O-sulfonic acid 4 with an excess of
an aqueous methylamine solution under conditions specified in
ref. 4 resulted in a mixture of the Z/E isomers of enamino-
nitriles (1-cyano-3,3-diethoxy-2-methylaminoprop-1-enes) 6a,b
The method of mixing of all of the three reactants was also
unsuccessful. The interaction of butynal 1a, hydroxylamine-O-
sulfonic acid and an excess of methylamine in water resulted in
a mixture of isomeric 5(3)-diethoxymethyl-1-methylpyrazoles
8a,b in 56% overall yield in place of expected diaziridine 5.
These pyrazoles were described previously with no spectroscopic
characterisation.19 We identified isomers 8a,b by 13C NMR
spectroscopy. In the spectrum of 8b, the multiplicity of a signal
(ddd) at 150.5 ppm due to the quaternary carbon atom of a
pyrazole ring is indicative of different spin–spin coupling con-
stants with protons of three CH groups, whereas in the spec-
trum of isomer 8a, the signal of such a carbon atom at 138.7 ppm
exhibits a more complex multiplicity because of the additional
EtO
EtO
i
C
C
CHO + MeNH2
C
C
CH NMe
EtO
EtO
1a
2
OEt
Me
EtO
C
C
H
N
N
3
spin–spin coupling constant JCNMe. In contrast, a signal at
Me
128.3 ppm due to the carbon atom of the NCH unit in the
spectrum of 8b exhibits a more complex multiplicity as com-
pared with the signal due to an analogous atom in isomer 8a. The
ratio between the isomers is 8a:8b = 3:2 (1H NMR data). The
3a
Scheme 1 Reagents and conditions: i, MeNH2 (1.2 mol), CHCl3, –10–0 °C,
1 h and 18–20 °C, 1 h; ii, MeNHCl (1.2 mol), CHCl3, MeNH2 (or Et3N),
20 °C, 10 h.
– 227 –

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, 2001, 11(6), 227–229
References
formation of a mixture of pyrazoles 8a,b is probably due to the fact
that an amine taken in an excess reacts not only with the alde-
hyde group to form α-amino alcohol 9 but also adds at the triple
bond of this compound to give intermediate 10. Next, both of
the products react with hydroxylamine-O-sulfonic acid in accord-
ance with Scheme 3.
1 E. Schmitz and K. Schinkovski, Chem. Ber., 1964, 97, 49.
2 V. Yu. Petukhova, V. V. Kuznetsov, A. V. Shevtsov, Yu. A. Strelenko,
N. N. Makhova, K. A. Lyssenko and M. Yu. Antipin, Izv. Akad. Nauk.,
Ser. Khim., 2001, 421 (Russ. Chem. Bull., 2001, 50, 440).
3 A. N. Mikhailyuk, N. N. Makhova, A. E. Bova, L. I. Khmel’nitskii and
S. S. Novikov, Izv. Akad. Nauk SSSR, Ser. Khim., 1978, 1566 (Bull.
Acad. Sci. USSR, Div. Chem. Sci., 1978, 27, 1376).
These results ultimately demonstrated that the diethoxymethyl
group in aldehyde 1a is insufficiently bulky for preventing the
reaction of the acetylene moiety with methylamine. Therefore,
the preparation of diaziridines based on this aldehyde can be
expected with only the use of equimolar amounts of the reac-
tants. Indeed, 1,2-dimethyl-3-(3,3-diethoxypropyn-1-yl)diaziridine
3a was prepared by the interaction of compound 1a, methyl-
amine and N-chloromethylamine in equimolar amounts in chloro-
form in the presence of potassium carbonate;10 however, the
yield was insignificant (5%). Only the reaction of compound 1a
with methylamine and N-methylhydroxylamine-O-sulfonic acid
(or N-chloromethylamine) in equimolar amounts in aqueous
methanol at controlled pH values resulted in diaziridine 3a in
considerable yield (20–34%) (Scheme 4). We found pH 9.0–9.5
to be optimum values. The specified conditions were also used
for the preparation of another 3-ethynyldiaziridine, 1,2-dimethyl-
3-(3-hydroxymethyl-3-methylbutyn-1-yl)diaziridine 3b, which
was synthesised from 4-hydroxymethyl-4-methypentyn-2-al 1b,
methylamine and N-chloromethylamine (Scheme 4).
Thus, we found conditions which allowed one to overcome
susceptibility of α-acetylenic aldehydes 1a,b to add amines not
only at the carbonyl group but also at the triple bond and syn-
thesised the first representatives of diaziridine derivatives 3a,b,†
in which the ethynyl unit is directly bound to the carbon atom
of the diaziridine ring. In this study, we also synthesised the
products of the addition of an amine or an aminating agent at
the triple bond of 4,4-diethoxybutyn-2-al 1a, a mixture of iso-
meric 5(3)-diethoxymethyl-1-methylpyrazoles 8a,b‡ and a mix-
ture of Z/E isomers of 1-cyano-3,3-diethoxy-2-methylamino-
prop-1-enes 6a,b.§
†
All new compounds exhibited satisfactory elemental analyses, and
their structures were confirmed by IR, H and 13C NMR spectroscopy.
1
IR spectra were measured on an UR-20 spectrometer in thin films of
pure substances or in KBr; H and 13C NMR spectra were recorded on
Bruker WM-250 (250 MHz) and Bruker AM-300 (75.5 MHz) spectrome-
ters, respectively (TMS was used as an internal standard). Mass spectra
were measured on a Finnigan MAT INCOS-50 instrument. TLC was
carried out on Silufol UV-254 plates.
The general method for the synthesis of diaziridines 3a,b from aldehydes
1a,b and N-chloromethylamine. An aqueous 25% methylamine solution
(2.5 ml, 20 mmol) was dropped into a solution of aldehyde 1a or 1b
(20 mmol) in 20 ml of a water–methanol mixture (1:1) at –10 °C. Then,
an aqueous N-chloromethylamine solution (10 ml, 40 mmol) obtained
from 5.0 ml (40 mmol) of methylamine and 5 ml (40 mmol) of tert-butyl
hypochlorite was added dropwise at –10 °C and pH 9–9.5; the reaction
mixture was stirred for 1 h at 0–5 °C and then for 3 h at 20 °C at the
specified pH value adjusted by the addition of a 20% aqueous NaOH
solution. The product was extracted with CHCl3, the solution obtained
was dried with K2CO3, the solvent was evaporated and the rest was
distilled at a reduced pressure.
1
6,6-Diethoxy-2-azahex-2-en-4-yne 2: yield 12%, bp 70 °C (1 Torr),
Rf 0.27 (CHCl3). H NMR (CD3Cl–CCl4) d: 1.15 (t, Me–C, 3J 7 Hz),
1
3.3 and 3.4 (2s, N–Me, 4J 2.5 Hz), 3.55 (m, CH2O), 5.1 [m, CH(OEt)2,
4J 2 Hz], 5.4 [m, CH(OEt)2, 4J 4 Hz], 7.4 (m, CH=, 4J 2.5 Hz). IR
(n/cm–1): 1050, 1130, 1310, 1350. 1600 (C=N), 2220 (CºC), 2870,
2970 (CH).
1,2-Dimethyl-3-(3,3-diethoxypropyn-1-yl)diaziridine 3a: yield 20% (with
MeNHOSO3H) or 34% (with MeNHCl), bp 68–69 °C (1 Torr), Rf 0.43
1
3
(MeOH). H NMR (CDCl3–CCl4) d: 1.16 (t, Me–C, J 7 Hz), 2.36 (s,
N–Me), 2.44 (s, N–Me) 2.86 (d, CH diaz. ring, 5J 1.2 Hz), 3.6 (m,
CH2O), 5.3 [m, CH(OEt)2, 5J 1.2 Hz]. 13C NMR (CDCl3–CCl4) d: 14.9 (dt,
C–Me, 1J 142.3 Hz, 2J 2.8 Hz), 42.0 (dq, N–Me, 1J 136.0 Hz, 3JCH diaz. ring
This work was supported by NATO (grant. no. SST. CLG
977566) and INTAS (grant no. 99-00157).
1
3
2.4 Hz), 47.3 (dq, N–Me, J 136.0 Hz, JCH diaz. ring 4.8 Hz), 54.0 (dsp,
1
3
1
2
CH diaz. ring, J 184.4 Hz, J 5.7 Hz), 60.7 (m, CH2O, J 142.3 Hz, J
4.6 Hz), 78.9 (dd, CºC, J 4.6 Hz, J 3.3 Hz), 81.72 (CºC, J = 3J =
= 3.6 Hz), 90.9 [m, CH(OEt)2, 1J 142.3 Hz, 3J 2.9 Hz]. IR (n/cm–1):
1000, 1050, 1120, 1150, 1350, 1430, 2240 (CºC), 2870, 2970 (CH).
MS, m/z: 166 (M+).
2
3
2
EtO
EtO
i
C
C
CHO + H2NOSO3H + MeNH2
i
5
1,2-Dimethyl-3-(3-hydroxymethyl-3-methylbutyn-1-yl)diaziridine 3b:
yield 38%, bp 73–75 °C (3 Torr). Rf 0.24 (CHCl3–hexane, 1:1). 1H NMR
(CDCl3) d: 1.52 (s, 6H, 2C–Me), 2.48 (s, 3H, N–Me), 2.55 (s, 3H,
N–Me), 2.75 (s, 1H, CHring), 4.11 (m, 2H, CH2O). 13C NMR (CDCl3) d:
31.35 (2Me–C), 41.55 (dq, N–Me, JH 136.3 Hz, JH ring 2.5 Hz), 47.16
(dq, N–Me, 1JH 136.1 Hz, 3JCH ring 4.9 Hz), 54.6 (CHring 1J 184.3 Hz, 3J
1a
EtO
EtO
NHMe
OH
EtO
EtO
NHMe
OH
1
3
C
CH CH
NHMe
10
C
C
CH
1
2
2.5, 4.9 Hz), 64.57 (CH –OH, J 139.50 Hz, J 4.4 Hz), 74.99 (–C C,
º
2JCH ring 4.5 Hz), 79.5 (C2ºC, 3JCH ring 4.4 Hz). IR (n/cm–1): 2230 (CºC),
2920, 2980 (CH), 3450 (OH). MS, m/z (%): 154.0 (M+, 9), 139.0 (56),
137.0 (75), 121.0 (22), 110.0 (56), 109.0 (81), 96.0 (52), 84.0 (44), 68.0
(100).
9
H2NOSO3H
H2NOSO3H
‡
The mixture of 3-diethoxymethyl-1-methyl- and 5-diethoxymethyl-1-
methylpyrazoles 8a,b: yield 54%, ratio 8a:8b = 3:2, bp 58–60 °C (1 Torr),
Rf 0.35 (CHCl3). IR (n/cm–1): 750, 1050, 1105, 1320, 1350, 1430, 1600,
2880, 2920, 2970. MS, m/z (%): 182 (M+, 2), 139 (100), 111 (95), 84
(30), 45 (26).
CH
CH
CH
NHMe
OH
EtO
EtO
EtO
EtO
C
CH
C
HO3SO HN
MeHN
NH OSO3H
NHMe
8a: 1H NMR (CDCl3) d: 1.14 (t, 6H, Me–C), 3.4–3.6 (m, 4H, CH2O),
3.81 (s, 3H, N–Me), 5.49 [m, 1H, CH(OEt)2], 6.2 [dd, 1H, C(4)Hring
,
4
3JC(5)H ring 2.0 Hz, JCH(OEt) 0.6 Hz], 7.29 [d, 1H, C(3)ring 3J 2.0 Hz].
,
13C NMR (CDCl3–CCl4) d:214.47 (dq, Me–C, 1J 126.2 Hz, 2JCH 2.6 Hz),
36.42 (q, N–Me, 1J 137.8 Hz), 60.17 (dt, CH2–O, 1J 142.8 Hz, 2J 2.6 Hz),
95.51 [d, CH(OEt)2, 1J 161.1 Hz, 3J 2.0 Hz], 105.27 [C(4)ring, 1J 176.9 Hz,
OEt
EtO
EtO
EtO
N
2JC(3)H ring 5.7 Hz, 3J
2.0 Hz], 136.64 [C(3)ring, 1J 184.4 Hz, 2JC(4)H ring
N
CH(OEt)2
N
5.7 Hz], 138.7 [compl. m, C(5)ring].
N
Me
8b: 1H NMR (CDCl3) d: 1.16 (t, 6H, Me–C), 3.4–3.6 (m, 4H, CH2O),
3.79 (s, 3H, N–Me), 5.47 [s, 1H, CH(OEt)2], 6.15 [dd, 1H, C(4)Hring
,
Me
3JC(5)H ring 2.3, 4JCH(OEt) 0.6 Hz], 7.20 [d, C(5)Hring, 3JC(4)H ring 2.3 Hz]. 13
C
2
8a
8b
1
2
NMR (CDCl3–CCl4) d: 14.58 (dq, Me–C, J 126.0 Hz, J 2.7 Hz), 37.9
1
3
2
(dq, N–Me, J 140.2 Hz, J 2.4 Hz), 60.17 (dt, CH2O, 1J 141.8 Hz, J
Scheme 3 Reagents and conditions: i, MeNH2 (10 mol), H2O, NH2OSO3H
(1.5 mol), 0–5 °C, then 18–20 °C, 4 h.
1
3
2.7 Hz), 97.2 [dd, CH(OEt)2, J 161.2 Hz, J 2.0 Hz], 103.28 [C(4)ring
,
2
3
1
1JCH 177.5 Hz, JC(5)H ring 8.4 Hz, JCH(OEt) 2.0 Hz], 129.36 [C(5)ring, J
184.7 Hz, 2JCH [C(4)H ring] 8.4 Hz, 3JN–Me 2.42Hz], 150.3 [ddd, C(3)ring].
– 228 –

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, 2001, 11(6), 227–229
4
5
A. N. Mikhailyuk, V. Yu. Petukhova and N. N. Makhova, Mendeleev
Commun., 1997, 60.
Yu. V. Zeifman, E. G. Abduganiev, E. M. Rokhlin and I. L. Knunyants,
Izv. Akad. Nauk SSSR, Ser. Khim., 1972, 2737 (Bull. Acad. Sci. USSR,
Div. Chem. Sci., 1972, 21, 2667).
R. G. Kostyanovsky, G. V. Shustov and V. I. Markov, Izv. Akad. Nauk
SSSR, Ser. Khim., 1974, 2823 (Bull. Acad. Sci. USSR, Div. Chem. Sci.,
1974, 23, 2725).
V. V. Kuznetsov, N. N. Makhova, Yu. A. Strelenko and L. I. Khmel’nitskii,
Izv. Akad. Nauk SSSR, Ser. Khim., 1991, 2861 (Bull. Acad. Sci. USSR,
Div. Chem. Sci., 1991, 40, 2496).
OEt
Me
EtO
C
C
H
EtO
EtO
N
6
7
C
C
CHO
N
1a
Me
3a
i
Me
CH2OH
C
8
9
V. V. Kuznetsov, N. N. Makhova and L. I. Khmel’nitskii, Izv. Akad.
Nauk, Ser. Khim., 1997, 1410 (Russ. Chem. Bull., 1997, 46, 1354).
V. V. Kuznetsov, N. N. Makhova and M. O. Dekaprilevich, Izv. Akad.
Nauk, Ser. Khim., 1999, 623 (Russ. Chem. Bull., 1999, 48, 617).
Me
Me
Me
C
C
C
CHO
Me
C
CH2OH
N
10 N. N. Makhova, A. N. Mikhailyuk, V. V. Kuznetsov, S. A. Kutepov and
P. A. Belyakov, Mendeleev Commun., 2000, 182.
H
1b
N
11 H. Hankli, M. Mintas and A. Mannschreck, Chem. Ber., 1979, 112,
2028.
12 A. Mannschreck, R. Radeglia, E. Grundemann and R. Ohme, Chem. Ber.,
1967, 100, 1778.
13 M. Mintas, A. Mannschreck and L. Klasinc, Tetrahedron, 1981, 37, 867.
14 N. A. Preobrazhensky, I. A. Rubtsov, T. F. Dankova and V. P. Pavlov,
Zh. Obshch. Khim., 1945, 15, 953 (in Russian).
Me
3b
Scheme 4 Reagents and conditions: i, MeNH2 (1 mol), MeNHCl (1.2 mol),
EtOH–H2O, pH 9.0–9.5 or MeNH2 (1 mol), MeNHOSO3H (1.2 mol), MeOH–
H2O, pH 9.0–9.5.
15 R. L. Bolshedvorskaya and L. I. Vereshyagin, Usp. Khim., 1973, 42,
511 (Russ. Chem. Rev., 1973, 42, 225).
16 A. I. Borisova, M. M. Demina, A. S. Medvedeva, I. D. Kalikman and
N. U. Vyasankin, Zh. Obshch. Khim., 1983, 53, 1310 [J. Gen. Chem.
USSR (Engl. Transl.), 1983, 53, 1173].
§
The mixture of Z/E 1-cyano-3,3-diethoxy-2-methylaminoprop-1-enes
6a,b (5:1): yield 65%, bp 98–100 °C (1 Torr), Rf 0.6 (ethyl acetate–
hexane, 1:1). IR (n/cm–1): 1050, 1100, 1360, 1600, 2190 (CºN), 2880,
2960 (CH), 3350 (NH). MS, m/z (%): 184 (M+, 56), 140 (71), 109 (76),
103 (100), 83 (51), 67 (32), 56 (49).
17 P. W. Hickmott, Tetrahedron, 1982, 38, 1975.
6a: 1H NMR (CDCl3) d: 1.18 (t, 6H, Me–C), 2.64 (d, 3H, N–Me,
3J 0.5 Hz), 3.4–3.7 (m, 4H, CH2O), 3.74 (s, 1H, =CH), 5.24 [m, 1H,
CH(OEt)2], 5.5 (br. s. 1H, NH). 13C NMR (CDCl3) d: 14.81 (dq, Me–C,
18 E. Murrey and G. Zweifel, Synthesis, 1980, 150.
19 N. I. Shapranova and I. N. Somin, Khim. Geterotsikl. Soedin., 1970,
404 [Chem. Heterocycl. Compd. (Engl. Transl.), 1970, 6, 374].
1J 126.5 Hz, J 2.8 Hz), 28.8 (N–Me, J 137.6 Hz, JNH 3.1 Hz), 59.17
(=CH, 1J 167.9 Hz), 63.18 (dt, CH2O, 1J 142.9, 2J 2.8 Hz), 97.8 [CH(OEt)2,
1J 164.5 Hz], 120.0 (CºN, 2J=CH 1.3 Hz), 160.2 (C=).
2
1
2
6b: 1H NMR (CDCl3) d: 1.15 (t, 6H, Me), 3.11 (d, 3H, N–Me, 3J 0.5 Hz),
3.4–3.7 (m, 4H, CH2O), 3.94 (s, 1H, =CH), 4.72 [m, 1H, CH(OEt)2], 5.5
(br. s, 1H, NH). 13C NMR (CDCl3) d: 14.75 (dq, Me–C, 1J 126.5 Hz,
2JCH O 2.8 Hz), 30.70 (N–Me, J 138.3 Hz), 57.67 (=CH, J 169.5 Hz),
1
1
2
61.55 (dt, CH2O, 1J 142.8 Hz, 2J 2.8 Hz), 98.9 [CH(OEt)2, 1J 164.3 Hz],
121.5 (CºN), 157.6 (C=).
1-Cyano-3,3-diethoxyprop-1-yne 7: yield 52%, bp 61–63 °C, Rf 0.78
(CHCl3). 1H NMR (CCl4) d: 1.2 (t, 6H, Me–C), 3.5–3.8 (m, 4H, CH2O),
1
2
5.3 [m, 1H, CH(OEt)2]. 13C NMR (CCl4) d: 14.79 (Me, J 126.8 Hz, J
3
1
2.7 Hz), 58.56 (CºC–CN, JCH(OEt) 3.9 Hz), 61.9 (CH2O, J 143.4 Hz,
2
2J 2.7, 3J 2.9 Hz), 79.3 (C–CºC, JCH(OEt) 3.3 Hz), 90.8 [CH(OEt)2,
2
2
1J 169.5 Hz, 3J 2.9 Hz], 104.2 (CºN, 4JCH(OEt) 1.9 Hz). IR (n/cm–1): 910,
2
Received: 13th July 2001; Com. 01/1826
1060, 1140, 1330, 1450, 2160 (CºC), 2310 (CºN), 2900, 2990 (CH).
– 229 –