Tris silane with aryl iodide

Diastereoselective syntheses of dihydrobenzo[f>]furans have been accomplished by a rhodium-catalyzed regioselective and enantiospecific intermolecular allylic etherification of o-iodophenols as a key step, providing the corresponding aryl ally ether 122, which leads to a dihydrobenzo[b]furan by treatment of the intermediate aryl iodide with tris(trimethylsilyl)silane and triethylborane at room temperature in the presence of air <00JA5012>. 

This methodology was applied to a two-step sequence for the preparation of enantio-merically enriched dihydrobenzo[h]furans (Scheme 10.11) [46]. Rhodium-catalyzed allylic etherification of (S)-47 (>99% ee), with the sodium anion of 2-iodo-6-methyl-phenol, furnished the corresponding aryl allyl ethers (S)-48/49 as a 28 1 mixture of regioisomers favoring (S)-48 (92% cee). Treatment of the aryl iodide (S)-48 with tris(trimethylsilyl)silane and triethylborane furnished the dihydrobenzo[h]furan derivatives 50a/50b as a 29 1 mixture of diastereomers [43]. 

Hydrazobenzenes with a chalcogenophosphoryl group were prepared by the reduction of 2-iodoazobenzene with hydrazine hydrate followed by a Pd(ii)-cata-lyzed cross-coupling with diphenylphosphine. The P(in) function was subsequently oxidised by hydrogen peroxide, sulfur and selenixun (Scheme 22) It was possible to restore the azobenzene structure by oxidation. The radical phosphination of aryl iodides by chlorodiphenylphosphine in the presence of tris(trimethylsilyl)silane, 1,1 -azobis(cyclohexane-l-carbonitrile) (V-40) and pyridine led to aryldiphenylphos-phines that were converted to the P-sulfides (Scheme 23). ... 

Transition Metal-catalyzed Reactions. Chlorodimethylvinyl-silane has been used in the synthesis of silyl-containing Heck reaction precursors.24 Heck reaction of aryl or alkenyl iodides with dimethylvinylsilylpyridine (36) using Pd2(dba)3 and tri-2-furylphosphine (TFP) produced the coupled alkene products 37 (R = Ph, 2-py, 2-thiophene, and others) in high yields and with exclusive E selectivity due to the pyridine directing group (eq 17). The pyridine moiety was also employed as a phase tag, which enabled easy purification via acid-base extraction. The silicon linker was subsequently cleaved by H2O2 oxidation. ... 

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