A NEW ROUTE TO SILAHETEROCYCLES AND PHOSPHAHETEROCYCLES - NUCLEOPHILIC AMINOMETHYLATION

The aminals tetramethylmethylenediamine (TMMDA) 1a, dicyclohexyldimeth ylmethylenediamine (CMMDA) 1b, and diisopropyldimethylmethylenediamine (IMMDA) 1c are doubly metalated by LitBu to give LiCH2N(R)CH2N(R)CH2L i [2a: R = Me, 2b: R = Cy (Cy = cyclohexyl), 2c: R = iPr], which preci pitate out of pentane as highly pyrophoric substances. Deuteration con firms N-methyl metalation exclusively. A series of aminomethylation re actions were performed by means of the doubly lithiated aminals 2a-c. The reactions of 2a-c with monochlorosilanes yield the silylated speci es R'3SiCH2N(R) CH2N(R)CH2SiR'(3) (3a: R'= Me, R = Me; 3b: R' = Me, R = Cy; 3c: R'= Me, R = iPr; 4: R'= Ph, R = Me, see Scheme 2). The use o f dichlorosilanes lead to six-membered heterocycles 6a-6d. 6a is trans ferred into a mono quarternary ammonium salt 7 by methylation with MeI . The spirocycle 8 is obtained from SiCl4 and two equivalents of 2a. S imilarly several substituted 1,3-diaza-5-phosphacyclohexanes 9a-e (R-1 = Me, Ph, NPh2, NCy2, see Scheme 3) are synthesized by the reaction o f dichlorophosphanes (RPCl2)-P-1 with 2a and 2b, respectively. Oxidati on of 9d with sulfur yields 12a, which is characterized by X-ray struc ture determination.