Vinyl and aryl metals

As predicted in COFGT (1995) <1995COFGT(2)951>, several new and modified methods for the preparations of vinyl and aryl metals have been discovered. Because of the opportunity for formation of two or more C−C bonds in one reaction and the excellent atom economy of these reactions, the use of vinyl and aryl metals in synthesis will continue to grow. In this final section, some methods which could not be easily placed in any category defined in COFGT (1995) are presented. The diorganocuprate 51, prepared by the reaction of the cuprate 53 and lithiated dihydrofuran 52, rearranges to vinylcuprate 54 which reacts with iodine to give the vinyl iodide. Similarly, lithium furan 55 is converted into ketone 56 via vinylcuprate 57 (Scheme 39) <2003JOC4008>. (Formula presented) Ketene (S,Te)-acetals can be prepared via a Wittig–Horner-type reaction as shown in Scheme 40 <1999T7421>. Thiophosphonates, which can be prepared from triethylphosphonate and chloromethylphenyl- or methyl sulfide, are condensed with aldehydes in good yield. Aromatic aldehydes give good yields of ketene acetals, whereas aliphatic aldehydes provide lower yields (Scheme 40) and ketones do not react at all under these conditions. (Formula presented) The organylselenolate and organyltellurolate anions, generated from diorganylditellurides and sodium borohydride, react with alkynylphosphonates (Equation (18)). The addition occurs at the β-carbon with (Z)-stereochemistry. This is rationalized in terms of Michael-type addition with a carbanion stabilization by the diethoxyphosphinyl group <2000TL161>. (Formula presented) The aryl iodides 58 when treated with tris(trimethylsilyl)silane (TTMS) under standard radical conditions give benzoseleno- or tellurophenes 59 (Equation (19))....