<i>C</i>‐Nitroso compounds. Part XXXVII. The reactivity of α‐chloronitroso compounds towards organoaluminium reagents

Abstract

Abstract With sterically unhindered and certain moderately hindered α‐chloronitroso compounds 1 trimethylaluminium at low temperature gives, via complexes 2 and 3 , the methyl nitrones 4 (Scheme 1). Several intermediate complexes 3 lose methane upon heating and rearrange to α‐chloroimines 5 (Scheme 2), the structure of which is determined by that of the precursors ( E ‐ or Z ‐geometry; cf. Scheme 6). More sterically hindered α‐chloronitroso compounds containing quaternary carbon undergo C‐C rupture when treated with trimethylaluminium, thus forming hydroxamic acid chlorides, formally HCI adducts of nitrile oxides ( cf. 8j in Scheme 3; 8k in Scheme 4). In the latter case, subsequent reactions lead to overall ring enlargement, i.e. formation of the seven‐membered cyclic oxime 12. With triethyl‐aluminium and triisobutylaluminium, α‐chloronitroso compounds are mainly reduced to oximes and the isomeric amides (Scheme 7).