Organolithium reagents, addition sulfurization

The chemical behavior of heteroatom-substituted vinylcarbene complexes is similar to that of a,(3-unsaturated carbonyl compounds (Figure 2.17) [206]. It is possible to perform Michael additions [217,230], 1,4-addition of cuprates [151], additions of nucleophilic radicals [231], 1,3-dipolar cycloadditions [232,233], inter-[234-241] or intramolecular [220,242] Diels-Alder reactions, as well as Simmons-Smith- [243], sulfur ylide- [244] or diazomethane-mediated [151] cyclopropanati-ons of the vinylcarbene C-C double bond. The treatment of arylcarbene complexes with organolithium reagents ean lead via conjugate addition to substituted 1,4-cyclohexadien-6-ylidene complexes [245]. 

Michael additions of organolithium, Grignard, and diorganozinc reagents to enones and other rt, -unsaturated carbonyl compounds are catalyzed inter alia by copper, nickel and cobalt salts. The best results are obtained with cop-per(I) catalysts, especially those in which copper is bound to a soft , readily polarizable center (sulfur or phosphorus). 

The corresponding organolithium species Me3SiCH2Li, prepared from the chloride and lithium metal, or by bromine- or iodine-lithium exchange with butyl-lithium or sulfur-lithium exchange with lithium naphthalenide, can also prove effective. Addition of CeCls to this organolithium species provides a softer reagent that allows its use with sensitive carbonyl compounds. ... 

The first metal-ate complex, sodium triethylzincate, " was obtained by John Wanklyn who treated diethylzinc with elemental sodium in an attempt to produce ethylsodium. A systematic and reliable approach to ate complexes is the addition of a more polar organometallic reagent (eg., an organolithium) to a less polar organic derivative of an alkali-earth metal, transition element, or metalloid. In this way, a wealth of ate complexes of berrylium, magnesium, zinc, copper, boron, aluminum, silicon, tin, and mercury as well as of nonmetals like phosphorus, sulfur, selenium, tellurium, and even iodine " have been obtained. 

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