2-(t-Butylamino)-3-methyl-2-butenenitrile

(1; R1 = R2 = R3 = Me)

[66875-75-0]  · C6H10N2  · 2-(Methylamino)-3-methyl-2-butenenitrile  · (MW 110.16) (2; R1 = R2 = Me, R3 = Et)

[73404-99-6]  · C7H12N2  · 2-(Ethylamino)-3-methyl-2-butenenitrile  · (MW 124.19) (3; R1 = R2 = Me, R3 = i-Pr)

[63364-15-8]  · C8H14N2  · 2-(Isopropylamino)-3-methyl-2-butenenitrile  · (MW 138.21) (4; R1 = R2 = Me, R3 = t-Bu)

[63364-14-7]  · C9H16N2  · 2-(t-Butylamino)-3-methyl-2-butenenitrile  · (MW 152.24) (5; R1 = R2 = Me, R3 = Cy)

[63364-25-0]  · C11H18N2  · 2-(Cyclohexylamino)-3-methyl-2-butenenitrile  · (MW 178.27) (6; R1 = Me, R2 = Et, R3 = i-Pr)

[66102-53-2]  · C9H16N2  · 2-(Isopropylamino)-3-methyl-2-pentenenitrile  · (MW 152.24) (7; R1 = Me, R2 = Et, R3 = t-Bu)

[66102-54-3]  · C10H18N2  · 2-(t-Butylamino)-3-methyl-2-pentenenitrile  · (MW 166.27) (8; R1 = R2 = Et, R3 = i-Pr)

[66102-55-4]  · C10H18N2  · 2-(Isopropylamino)-3-ethyl-2-pentenenitrile  · (MW 166.27) (9; R1 = R2 = Et, R3 = t-Bu)

[63364-26-1]  · C11H20N2  · 2-(t-Butylamino)-3-ethyl-2-pentenenitrile  · (MW 180.30) (10; R1 = R2 = Et, R3 = Cy)

[63364-27-2]  · C13H22N2  · 2-(Cyclohexylamino)-3-ethyl-2-pentenenitrile  · (MW 206.33) (11; R1,R2 = -(CH2)5-, R3 = i-Pr)

[73171-65-0]  · C11H18N2  · Cyclohexylidene(isopropylamino)acetonitrile  · (MW 178.27) (12; R1,R2 = -(CH2)5-, R3 = t-Bu)

[63364-28-3]  · C12H20N2  · t-Butylamino(cyclohexylidene)acetonitrile  · (MW 192.30) (13; R1,R2 = -(CH2)5-, R3 = Cy)

[63364-29-4]  · C14H22N2  · Cyclohexylamino(cyclohexylidene)acetonitrile  · (MW 218.34)

(geminal donor-acceptor-substituted alkenes;1 for synthesis of trialkylketenimines and -amidines,2,3 a-functionalized imidoyl cyanides,4 carboxylic amides,5 and 1-aza-2-cyano-1,3-dienes6)

Alternate Names: N-t-butyl-b,b-dimethyl-a-cyanoenamine; 2-(t-butylamino)-3-methylcrotononitrile.

Physical Data: bp (1) 97-98 °C/21 mmHg; (2) 89-94 °C/15 mmHg; (3) 95-96 °C/12 mmHg; (4) 112-117 °C/14 mmHg; (5) 135-146 °C/12 mmHg; (6) 94-101 °C/11 mmHg; (8) 98-100 °C/11 mmHg; (9) 110-114 °C/12 mmHg; (10) 146-157 °C/12 mmHg; (11) 83 °C/0.017 mmHg; (13) 115-125 °C/0.05 mmHg; mp (3) 30 °C; (11) 44 °C.

Solubility: sol most organic solvents; compatible with all solvents.

Form Supplied in: commercially available (R1 = R2 = Me, R3 = i-Pr, t-Bu) as colorless liquid or low-melting solid.

Analysis of Reagent Purity: 1H NMR (GC cannot be used as these reagents are subject to tautomerize into stable imidoyl cyanides).

Preparative Methods: highly reproducible synthesis from cyanation of a-chloro aldimines with potassium cyanide in methanol under reflux (eq 1).6 This reaction is amenable to large-scale preparation (1-2 mol) and synthesis of several higher homologs.6,7 DMSO, DMF, or water can be used as well in these cyanation reactions.4

Handling, Storage, and Precautions: these reagents are stable for a long period at -20 °C. Stable at rt for several weeks. As the reagents might act as a cyanide source, use in a well-ventilated fume hood is recommended.

Introduction.

a-Cyano enamines are a class of geminal donor-acceptor-substituted alkenes.1 Upon heating, e.g. distillation in vacuo or gas chromatographic analysis, a-cyano enamines tautomerize partially into imidoyl cyanides (eq 2).6 Both a-cyano enamines and imidoyl cyanides are stable isolable species.

Synthesis of Trialkylketenimines and Amidines.

Numerous syntheses of ketenimines, having at least one aryl substituent on carbon or nitrogen, have been reported hitherto. The rare and labile trialkylketenimines are easily accessible from a-cyano enamines by reaction with methylmagnesium iodide or Methyllithium in diethyl ether (eq 3).2,3 Trialkylketenimines may be isolated or treated in situ with primary amines to afford amidines (eq 4).2

Functional Group Transformation of Aldehydes into Carboxylic Amides.

Heating of a-cyano enamines with dry hydrogen chloride in an anhydrous alcohol, e.g. methanol, ethanol, or n-butanol, produces carboxylic amides and the corresponding alkyl chlorides (eqs 5 and 6).5 The intermediate enammonium chlorides are accessible by reaction of a-cyano enamines with dry Hydrogen Chloride in benzene (eq 5).8 As a-cyano enamines are easily accessible from aldehydes, this conversion corresponds to the transformation of an aldehyde into a carboxylic amide.9

Synthesis of Functionalized Imidoyl Cyanides.

a-Cyano enamines react instantaneously in CCl4 at rt with N-Bromosuccinimide and N-Chlorosuccinimide to give access to stable a-chloro- and a-bromoimidoyl cyanides (with practically no limitations in the substitution pattern of higher analogs) (eq 7).4 The a-halo substituent of these trifunctional compounds is easily displaced by nucleophiles, such as thiolates, to give a-sulfenylated imidoyl cyanides (eq 8).10 On the other hand, a-bromoimidoyl cyanides are readily converted into 1-aza-2-cyano-1,3-dienes by treatment with Sodium Methoxide in methanol under reflux (eq 9).10

Synthesis of Nontautomerizable a-Cyano Enamines.

N-Alkylation of tautomerizable a-cyano enamines is readily accomplished with a variety of alkylating agents, including alkyl fluorosulfonates, dialkyl sulfates, or Triethyloxonium Tetrafluoroborate (eq 10).11

Similar a-cyano enamines may also be obtained by reaction of a-chloro enamines with Potassium Cyanide (eq 11).12 Addition of organolithium reagents to the cyano group followed by acidic hydrolysis provides a-diketones.12


1. De Kimpe, N.; Verhé, R.; De Buyck, L.; Schamp, N. CB 1983, 116, 3846.
2. De Kimpe, N.; Verhé, R.; De Buyck, L.; Chys, J.; Schamp, N. JOC 1978, 43, 2670.
3. De Kimpe, N.; Verhé, R.; De Buyck, L.; Schamp, N. OPP 1982, 14, 213.
4. De Kimpe, N.; Verhé, R.; De Buyck, L.; Chys, J.; Schamp, N. SC 1979, 9, 901.
5. De Kimpe, N.; Verhé, R.; De Buyck, L.; Chys, J.; Schamp, N. BSB 1979, 88, 695.
6. De Kimpe, N.; Verhé, R.; De Buyck, L.; Hasma, H.; Schamp, N. T 1976, 32, 3063.
7. De Kimpe, N.; Verhé, R.; De Buyck, L.; Chys, J.; Schamp, N. S 1978, 895.
8. De Kimpe, N.; Verhé, R.; De Buyck, L.; Schamp, N. BSB 1979, 88, 59.
9. De Kimpe, N.; Verhé, R.; De Buyck, L.; Chys, J.; Schamp, N. OPP 1978, 10, 149.
10. De Kimpe, N.; Verhé, R.; De Buyck, L.; Chys, J.; Schamp, N. BSB 1979, 88, 695.
11. De Kimpe, N.; Verhé, R.; De Buyck, L.; Schamp, N. S 1979, 741.
12. Toye, J.; Ghosez, L. JACS 1975, 97, 2276.

Norbert De Kimpe

University of Gent, Belgium



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