7144
a-Deoxysilylation of Hydroxylamine Derivatives. A New Method for Nitrene Generation Sir : Elimination of alkoxysilanes according to eq 1, which may be described as an a-deoxysilylation process, FOR
%Mb
A [R,M] +
R,SiOR
(1)
SiR3 I, M = C,Si; n = 2 2, M = N , n = l /OSi(CHJ, C&N\ Si(CH,), 2a
,OCHJ /OSi(CH,), C6H6N\ CHJ\ Si(CHJ3 Si(CH,X 2b
components. The yield of aniline is not appreciably altered by hearing 2a in either toluene or cyclohexane, although the latter solvent does yield a small amount of N-cyclohexylaniline (12, 5 %, vpc), as expected4” for 3. Formation of products 6 and 8-10 from 2a in cyclohexene is neatly accommodated by application and simple extension of k n ~ w n ~interniolecular ~b~ reaction modes for ground state (triplet) 3, and it should be emphasized that isolation of 7 is particularly significant, since there is currently little evidence that arylnitrenes (whether singlet or triplet) form aziridines by reaction with any Kinetic studies which address this important point and are designed to exclude conceivable non-nitrene pathways to 7 are in progress. L ?n.C,H,Li
2C
C6H5N(OH)H
has been heretofore restricted to pyrolyses of systems (1) wherein the central atom (M) is a member of the We group IV elements, viz., carbon’ and now report preliminary product and kinetic studies which indicate that the scope of eq 1 may be usefully extended to nitrene (RN:) generation via pyrolysis of molecules in which the elimination center is nitrogen (2), the first representative of group V elements. For comparative purposes, our initial investigations focused on hydroxylamine derivatives that would in principle generate phenylnitrene (3), since a considerable body of data4” is available on this reactive intermediate. Thus, N,O-bis(trimethylsily1)phenylhydroxylamine5 (2a) bas prepared (20 nonoptimized) from N-phenylhydroxylamine (4) according to the reaction sequence in eq 2. The propensity of 2a toward fragmentation according to eq 1 was first evidenced by its mass spectrum (70 eV), which featured a relatively weak parent ion and a base peak at m/e 91, presumably due to [C6H&:]+. This tentative conclusion was substantiated by the observation that 2a undergoes essentially complete reaction at 100” (16 hr) in cyclohexene (0.1 M ) to yield hexamethyldisiloxane (5, ca. 100 %, vpc), and at least eight additional products (vpc). Preparative vpc of this mixture led to isolation and identification (ir, nmr) of aniline (6, 20 %), 7-phenyl-7secondary amine 8 azabicyclo[4.1 .0]heptane6 (7, 2 (4 %), and bicyclohexyldiene’ 9. Trace amounts (
