Copper(I) Oxide-t-Butyl Isocyanide

Cu2O.[t-BuNC]m
(Cu2O)

[1317-39-1]  · Cu2O  · Copper(I) Oxide-t-Butyl Isocyanide  · (MW 143.08) (t-BuNC)

[7188-38-7]  · C5H9N  · Copper(I) Oxide-t-Butyl Isocyanide  · (MW 83.13)

(precursor to organocopper compounds reacting in aldol- and Michael-type fashion; cyclopropanation reagent; used in heterocycle synthesis)

Physical Data: reagent prepared in situ; see entries for Copper(I) Oxide and t-Butyl Isocyanide.

Solubility: sl sol H2O; sol common organic solvents.

Form Supplied in: t-BuNC: liquid; purified by distillation.

Preparative Methods: t-butyl isocyanide may be prepared by dehydration of the corresponding N-t-butylformamide.1 The reagent is generated in situ by mixing t-butyl isocyanide with copper(I) oxide (or copper powder) under nitrogen prior to use. Reactions with copper(0) are described below.

Handling, Storage, and Precautions: t-BuNC is flammable and highly toxic. All reactions should be conducted in a well-ventilated fume hood.

Aldol and Michael Reactions: Heterocycle Synthesis.

Copper(I) oxide-t-butyl isocyanide and copper(0)-t-butyl isocyanide react with active methylene compounds to form the corresponding organocopper(I) complexes with the accompanying formation of H2O and H2, respectively.2 The reaction mixture thus obtained reacts with ketones and aldehydes in the manner of the aldol condensation2 and with a,b-unsaturated carbonyl and nitrile compounds in the manner of the Michael addition.2

Alkyl isocyanides having an active a-hydrogen react, in the presence of a catalytic amount of copper(I) oxide, with a,b-unsaturated carbonyl or nitrile compounds and with ketones or aldehydes, producing 1-pyrroline and 2-oxazoline derivatives, respectively (eqs 1 and 2).3

Copper(I) oxide-t-butyl isocyanide induces dimerization of a,b-unsaturated carbonyl and nitrile compounds (eq 3).4

Cyclopropanations: Use of Copper(0).

Copper(I) carbenoid intermediates, which may be generated in situ by the reactions of a-halo carboxylic acid esters and nitriles with copper(I) oxide-t-butyl isocyanide complexes, are used for cyclopropanation of electron-deficient alkenes (eq 4).5

When Copper powder is substituted for Cu2O, the resulting mixed reagent reacts with active halogen compounds, probably through an oxidative addition of the carbon-halogen bond, to generate organocopper compounds. Copper(0)-t-butyl isocyanide promotes cyclopropanation of a,b-unsaturated esters and nitriles with trichloromethyl compounds such as trichloroacetonitrile and trichloroacetate (eq 5).6

Similarly, as shown in eq 6, vinylcyclopropanes can be prepared in moderate yields by the reaction of 1,3- or 3,3-dichloropropenes with a,b-unsaturated esters.7

Allenes.

The reagent employing copper powder reductively transforms gem-dibromocyclopropanes to allenes (eqs 7 and 8).8


1. (a) Ugi, I.; Meyr, R. AG 1958, 70, 702. (b) Ugi, I.; Fetzer, U.; Eholzer, U.; Knupfer, H.; Offermann, K. AG(E) 1965, 4, 472.
2. Ito, Y.; Konoike, T.; Saegusa, T. JOM 1975, 85, 395.
3. Saegusa, T.; Ito, Y.; Kinoshita, H.; Tomita, S. JOC 1971, 36, 3316.
4. (a) Saegusa, T.; Ito, Y.; Tomita, S.; Kinoshita, H. JOC 1970, 35, 670. (b) Saegusa, T.; Ito, Y.; Kinoshita, H.; Tomita, S. BCJ 1970, 43, 877.
5. Saegusa, T.; Ito, Y.; Yonezawa, K.; Inubushi, Y.; Tomita, S. JACS 1971, 93, 4049.
6. (a) Saegusa, T.; Yonezawa, K.; Ito, Y. SC 1972, 2, 431. (b) Saegusa, T.; Yonezawa, K.; Murase, I.; Konoike, T.; Tomita, S.; Ito, Y. JOC 1973, 38, 2319.
7. Ito, Y.; Yonezawa, K.; Saegusa, T. JOC 1974, 39, 1763.
8. Ballatore, A.; Crozet, M. P.; Surzur, J.-M. TL 1979, 3073.

Yoshihiko Ito

Kyoto University, Japan



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