1,3-Dithiane-Derived Alkoxyamines as One-Carbon Radical Precursors

Abstract

A new method for the generation of C-2 centered radicals derived from 1,3-dithiane is presented. The radical precursors, 2-dialkylaminoxyl-1,3-dithianes, are readily prepared from 1,3-dithiane and stable nitroxides. Thermal reaction of 2-dialkylaminoxyl-1,3-dithianes with electron-deficient olefins affords carboaminoxylation products or oxidative addition products depending on the nitroxide used. The 2-dialkylaminoxyl-1,3-dithianes can also be used as initiators/regulators for the controlled living free radical polymerization of styrene.

Key words

radical chemistry - nitroxides - 1,3-dithianes - controlled radical polymerization - microwaves

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15

The microwave experiments were conducted using professional laboratory microwave equipment. A MLS-Ethos 1600 Mikrowellen System (Milestone) was used for the present studies. The reactions were run in 40 mL MLS-reaction high-pressure vessels (up to 15 bars), which contain pressure control valves. An advanced temperature control system from MLS allowing direct contactless temperature monitoring was used. The microwave power is continuously and dynamically adjusted to follow the defined temperature profile.

20

This compound decomposes in the absence of solvents, upon exposure to air.