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The lithium salts of the Me3Si‐ as well as Me3Si‐ and Me2SiF‐substituted Cyclotrisilazanes I and II react with tert‐butylacylchloride under ring contraction and formation of the cyclodisilazane‐silylester, Me3SiN(SiMe2–N)2SiMe2–O–CO–CMe3 ( 1 ). The lithium salt of the fluorodi‐methylsilyl‐substituted cyclotrisilazan III forms with benzoylchloride primarily in the analogous reaction the carboxy‐silyl‐amide, Me2SiF(N–SiMe2)2SiMe2–NH–CO–C6H5+ ( 2 ), which can be converted with III and benzoylchloride into the cyclodisilazane‐silylester, Me2SiF(NSiMe2)2SiMe2–O–CO–C6H5, ( 3 ). A silylester substituted six‐membered disila‐oxadiazine ( 4 ) is the result of the reaction of the lithiated cyclotrisilazane, (Me2SiNH)2, (Me2SiNLi) with tert‐butyl‐acylchloride. The reaction includes anionic ring contraction and can be rationilized by a process analogous to keto‐enol‐tautomerism. Dilithiated octamethyl‐cyclotetrasilazane, (Me2SiNHMe2SiNLi)2, reacts with tert‐butyl‐acylchloride or benzoylchloride in a molar ratio 1:2 to yield symmetrically acylestersubstituted cyclodisilazanes, (RCO–O–SiMe2–NSiMe2)2, R = C6H5 ( 5 ), CMe3 ( 6 ). The reaction mechanisms are discussed and the crystal structures of 2 and 6 are reported.  相似文献   
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Synthesis of Boryl-coupled Cyclotri- and -tetrasilazanes and four-membered Cycloborasilazanes – Thermal Decomposition to SiC and BN Dilithiated octamethylcyclotetrasilazane reacts with a difluoroboryl substituted cyclotrisilazane to give the BF coupled 6-8-6-membered cyclosilazane 1 , with Me2SiHCl structural isomeric cyclotetra- and cyclotrisilazanes of the type I and II, and with Me3SiCl structural isomeric cyclodisilazanes of the type III and IV are formed. The dilithium derivatives of the cyclosilazanes I and II as well as III and IV react with BF3 and a BF2-substituted cyclotrisilazane to give four-membered cyclo-borasilazanes which are coupled with a cyclodisilazane via a SiMe2-group ( 2 – 4 ). The six-membered cycloborasilazane 5 is a byproduct in the reaction with BF3. The reaction mechanisms are discussed. The pyrolysis with formation of SiC and BN and a crystal structure analysis were carried out with 1 .  相似文献   
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