Trimethylsilane, photolysis

Nitroso trimethylsilane MesSi-NO 44.8 1.0 187.4 4.2 Laser photolysis, MS detect. 1995KRA/NII... 

Irradiation of the diazocyclohexadienone (108) in the presence of isoprene affords the spiro-adduct (109), whereas the thermally induced reaction gives only (110), which is probably formed via (109) by a vinylcyclopropane rearrangement cf. p. 111). Photolysis if diazomethyltrimethylsilane with frans-but-2-ene gives the trans-cyclopropane (111) (23%) and olefin (112) (61%), consistent with singlet carbene formation. With ethylene, only 17% of cyclopropyl trimethylsilane was obtained, along with 30% of (112). The steric hindrance in tetramethylethylene completely prevented cyclopropane formation, as did electronic effects in fluoro-olefins. No... 

Isomerizations. The isomerization of 1 to thiolactone 55 occurs in DMSO solution in the presence of NaH. It is reported that photolysis of 1 in methanol also affords 55. The reaction of 1 with (trifiuoromethyl)trimethylsilane (Ruppert s reagent) in THF in the presence of fluoride yields the trifluoromethylated thi-etane 56 (eq 23). A plausible mechanism of the transformation is a ring-opening/ring-closure process initiated by nucleophilic addition of trifluoromethanide to the carbonyl group of 1. 

Photochemical Prenylation. Photolysis of (a,a-dimethyl-allyl)trimethylsilane in the presence of l-methyl-2-phenyl-l-pyrrolinium perchlorate leads to the formation of a (3,3-dimethyl-prop-2-en-l-yl)pyrrolidine as the sole regioisomer (eq 5). ... 

The rate of combination of trifluoromethyl radicals to form hexafluoro-ethane has been measured by the flash photolysis of trifluoromethyl iodide coupled with rapid-scan i.r. spectroscopy in the absence of an inert diluent (At, N2, or COt) carbon tetrafluoride and tetrafluoroethylene were also formed, presumably via fluorine atom abstraction from trifluoroiodomethane by hot trifluoromethyl radicals (c/. ref. 27). Photolysis of trifluoroiodomethane has been used in studies on (i) the direction of radical attack on 1,3,3,3-tetrafluoropropene [- CFj CHI CHFCF, (75%) + (CFa)jCH CHFl (25%)] (ii) the rates of hydrogen abstraction from ammonia, ammonia-ethylene oxide, silane, trimethylsilane, tetramethylsilane, and cycloalkanes and (iiQ the competitive addition of the CFj- radical to ethylene and vinylidene fluoride. Radicals formed by photolysis of the fluoroalkyl iodides CFJ, C FJ, n-C,F,I, (CF,)jCFI, (CFaljCHI, (CFalaCDI, (CFa)jCClI, and (CFa)iCPhI (the last was synthesized by treatment of CFs CPh CTj with CsF and iodine in DMF) have been... 

---