[695-64-7] · C6H10ClNO · 1-Chloro-1-nitrosocyclohexane · (MW 147.5)
(electrophilic [NH2+] for alkenes and can function as a dienophile for [4 + 2] reactions)
Physical Data: bp 52 °C/12 mmHg.
Solubility: sol in wide range of organic solvents.
Form Supplied in: solid; widely available.
Preparative Methods: the most commonly used method is the reaction of cyclohexanone oxime with a chlorinating agent such as t-Butyl Hypochlorite in trichlorofluoromethane (eq 1).1
1-Chloro-1-nitrosocyclohexane shows a wide range of reactivity towards different functional groups. Deboer first demonstrated the reactivity of this reagent by reacting it with allylic alkenes such as phenylpropene to give cyclohexylidene-N-(2-phenyl)-prop-1-en-3-yl nitrone hydrochloride in 76% yield (eq 2).2
Other authors have shown that this reagent can be used effectively in the synthesis of polyhydroxylated cyclohexyl derivatives, alkaloids, and amino acids. 1-Chloro-1-nitrosocyclohexane reacts with 1,3-butadiene in ethanol to give 3,6-dihydro-1,2-dioxine (eq 3).3 Kresze in 1981 reported a synthesis of polyhydroxy amino compounds by utilizing the reactivity of 1-chloro-1-nitroso compounds towards dienes such as trans-1,3-cyclohexadien-5,6-diyl diacetate (eq 4).4 In 1984, Kibayashi reported a facile route to naturally occurring tropane alkaloids.5 The approach employs a Diels-Alder cycloaddition of cyclohepta-1,3-dienes with nitroso compounds followed by an intramolecular C-N bond formation (eq 5).
Recently, Oppolzer demonstrated the use of 1-chloro-1-nitrosocyclohexane as a convenient electrophilic nitrogen source in the asymmetric synthesis of amino acids and a-hydroxyamino acids.6 Treatment of an N-alkylsultam with Sodium Hexamethyldisilazide followed by 1-chloro-1-nitrosocyclohexane gave diastereomerically pure crystalline N-hydroxy amino acids (eqs 6 and 7).
Gary E. Keck & Anandan Palani
University of Utah, Salt Lake City, UT, USA