The regiodivergent ring contraction of diastereomeric 2-silyl-5,6-dihydro-6-aryl-(2H)-pyrans via [1,2]- and [1,4]-Wittig rearrangements to the corresponding α-silylcyclopentenols or (α-cyclopropyl)acylsilanes favor the [1,4]-pathway by ortho and para directing groups in the aromatic appendage and/or by sterically demanding silyl groups. The [1,2]-pathway is dominant with meta directing or elect...

Starting from tris(trimethylsilyl)silane the novel 2-chloro-3,4-bis-tris(trimethylsilyl)silyl-cyclo-diphospha-diazenium-tetrachloridogallate salt (7) was prepared in a six step synthetic procedure including the synthesis of N-tris(trimethylsilyl)silyl-aminodichlorophosphine (4) and 1,3-dichloro-2,4-bis-tris(trimethylsilyl)silyl-cyclo-diphospha-diazane (5). All intermediate products along the re...

[reaction: see text] A new one-pot tandem aldol process is described in which a secondary epoxy silyl ether is converted into the 1,5-bis-silyloxy-3-alkanone in good yield. Thus, treatment of the epoxy silyl ether 8 with TBSOTf and base affords the silyl enol ether 9 via non-aldol aldol rearrangement and addition of benzaldehyde and TBSOTf gives the ketone 10 with 4:1 syn selectivity. The diast...

Silanes, Silylbenzenes, Di(silyl)benzenes. Bromo(silyl)benzenes 1,2-Di(silyl)benzene (3). has been prepared in a three-step process starting with the reac­ tion of 1 ,2-dibromobenzene and /?-tolyl(chloro)silane with magnesium in tetrahydrofuran, which affords l,2-bis(p-tolylsilyl)benzene (1) as a stable high-yield intermediate. Compound 1 has been converted into 1 .2-bis(trifluoromethanesulfona...

 A simple, mild and practical procedure has been developed for the synthesis of symmetrical and unsymmetrical ethers by using DMSO, TBAI in the presence of K2CO3. We extended the utility of  Potassium carbonate as an efficient base for the preparation of ethers. A wide range of alkyl aryl and dialkyl ethers are synthesized from treatment of aliphatic alcohols and phenols with various alkyl hali...