TRICYCLIC HETEROCYCLES WITH BIFUNCTIONAL SILICON CENTERS

Article abstract of DOI:10.1016/S0022-328X(00)99678-5

Condensation of the diorganometallic reagents, (o-MC6H4)2X (M = Li, MgCl) with HSiCl3 followed by reduction with LiAlH4 provides dibenzosilacycles, I (a, X = -; b, X = NMe; c, X = CH2; d, X = CH2CH2) with two exocyclic H-substituents, =SiH2.Conditions for the stepwise conversion of I to mixed bifunctional systems, =SiHX (II, X = Cl, Br; III, X = OR), and bifunctional derivatives, =SiX2 (IV, X = Cl; V, X = OR) were determined.Controlled halogenation of I to II was accomplished with one molar equivalent of SO2Cl2 or NBS although CCl4 in the presence of ClRh(PPh3)3 or PdCl2 results in slow monochlorination.The reaction of I with excess SOCl2 or SO2Cl2 converts I to III but the latter is faster and provides fewer side reactions.Conversion of I to IV with excess alcohols occurs in high yield with ClRh(PPh3)3 but in low yield with H2PtCl6.Controlled alcoholysis of I to III could not be achieved except with ^tBuOH.The dichlorides, IV, are methylated in high yield to VII, =SiMe2.Reaction of Ib with ClRh(PPh3)3 results in elimination of H2 and formation of disilanes as indicated by trapping reactions with alcohols (formation of Vb).