Carol K. Haas

Reactions of siliranes with elemental sulfur and with t-butyl mercaptan. Preparation of the 2,3-dithia-1-silacyclopentane ring system

Abstract The reaction of 1,1-dimethyl- trans -2,3,-bis(2′,2′-dimethylcyclopropylidene)-1-silirane with S 8 gives a mixture of four isomeric products derived from incorporation of one sulfur atom and a cyclopropylcarbinyl-to-butenyl type rearrangement. This silirane reacts with t-butyl mercaptan to give a product of mercaptan addition in which a cyclopropylcarbinyl-to-butenyl rearrangement also has occurred. Hexamethylsilirane reacts with S 8 to give 1,1,4,4,5,5-hexamethyl-2,3-dithia-1-silacyclopentane in high yield. These reactions are discussed in terms of free radical mechanisms.

The extraordinary reactivity of the ring SiC bonds in 1,1-dimethyl-trans-2,3-bis(2′,2′-dimethylcyclopropylidene)-1-silacyclopropane

The reactions of the title silirane with oxygen, water, alcohols, primary and some secondary amines, hydrogen sulfide, carboxylic acids and hydrazoic acid proceeded exothermally at room temperature with opening of the SiC bond of the SiC2 ring. Hydrogen chloride reacted rapidly at −78°C, as did methyl- and phenyl-lithium and lithium dialkylamides. Ring cleavage of the silirane also could be effected with acetyl chloride, boron trichloride and lithium aluminum hydride. A comparison of the reactivity of the title silirane with that of 1,1-dimethyl-1-silacyclobutane shows the dramatic effect of the high ring strain in the former, which results in hyper-reactive ring SiC bonds.

Halomethyl—metal compounds : LXXVIII. Cyclohexyl- and /gb-phenylethyl-(trihalomethyl)mercury compounds as dihalocarbene precursors at room temperature

Abstract Alkyl(trihalomethyl)mercury compounds, RHgCXYBr (R = cyclohexyl and PhCH 2 CH 2 ; X, Y = Cl, Cl; Cl, Br; Br, Br) as well as the corresponding RHgCCl 3 compounds have been prepared and evaluated as divalent carbon transfer reagents. All were found to be much more reactive than the corresponding phenyl(trihalomethyl)mercurials. The cyclo-C 6 H 11 HgCXYBr (X, Y = Cl, Cl; Cl, Br) compounds were found to be quite effective carbene transfer reagents at room temperature.

Cyclohexyl(trihalomethyl)mercury compounds: Very reactive dihalocarbene precursors

Abstract The cyclohexyl(trihalomethyl)mercurials, RHgCCl 3 , RHgCCl 2 Br, RHgCClBr 2 and RHgCBr 3 (R = cyclohexyl), have been prepared and have been found to be excellent dihalocarbene sources. They transfer their CX 2 very rapidly at 80° and within 2–3 days at room temperature.