Matteson homologation

Typical protocols for the preparation of chiral allyl boronates involve Matteson homologation of vinyl boronates 159 with halomethyl lithium 160 or the vinylation of halomethyl boronate 163 with vinyl Grignard 162 followed by transesterification with dialkyl tartrate 164 (Scheme 26) <1996JOC100>. 

Pietruska and coworkers reported asymmetric cyclopropanation of chiral B-vinyl-l,3,2-dioxaborolanes with diazomethane in the presence of Pd catalyst 58) (Figure 14). The cyclopropylboronates were utilized for subsequent reactions, such as Suzuki coupling, Matteson homologation, etc. 

The treatment of arylboronic acids and esters with alkaline hydrogen peroxide to produce the corresponding phenols was first reported more than 75 years ago [324]. The oxidation of alkyl- and alkenyl- boronic acid derivatives leads to alkanols [40] and alde-hydes/ketones, respectively [85, 257, 279, 316]. With a-chiral alkylboronates, the re-action proceeds by retention of configuration (Equation 53, Figure 1.32) [359, 121]. In fact, the oxidation of boronic acids and esters is a synthetically useful process, mainly in the preparation of chiral aliphatic alcohols via asymmetric hydroboration reactions [300, 302], or from Matteson homologation chemistry [322]. Paradoxically, the... 

Alkenylboronates can be converted into functionalized allylboronates such as 42 by way of a Matteson homologation (Equation 24) [63-65]. This strategy is the reverse of the addition of alkenylmetal intermediates to halomethylboronates described in Section 6.2.1.2. It is an attractive method because the requisite alkenylboronates are readily prepared by the hydroboration of terminal alkynes. Differentially substituted 3,3-dialkyl allylboronates, a class of reagents that would be difficult to access otherwise, were synthesized using this route [66]. The use of Cl2CHLi as reagent in this method... 

Brown and co-workers employed a related three-carbon variant of the Matteson homologation chemistry to access a-alkyl- and a-aryl allylboronates such as 44 from chloroallylic carbanion 43 (Equation 25) [69]. 

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