Union of Type II Anion Relay Chemistry (ARC) with Pd-induced Cross Coupling Reactions (CCR) has been achieved, in conjunction with the design, synthesis, and evaluation of a new class of bifunctional linchpins, comprising a series of vinyl silanes bearing β-or γ-electrophilic sites. The synthetic tactic permits both alkylation and Pd-mediated CCR of the anions derived via 1,4-silyl C (sp 2 )→O Brook Rearrangements.Type I and II Anion Relay Chemistry (ARC), 1 exploiting Brook Rearrangements (Scheme 1A and 1B), 2 comprises a powerful linchpin tactic for the rapid assembly of high levels of molecular complexity, as demanded by natural product total synthesis. Extension of the Type II ARC process (Scheme 1B) to include transition metal promoted Cross-Coupling Reactions (CCR), as the culminating event in the Type II ARC process (cf. 8→9) would, in general, greatly extend the scope of this evolving synthetic tactic. Recently, we recorded a single example employing ortho-TMS benzaldehyde 10 as linchpin that demonstrated the feasibility of uniting Anion Relay Chemistry with Pd-mediated cross coupling (Scheme 2). 3 The reaction sequence involved treatment of 10 with n-BuLi followed in turn by addition of CuI and HMPA to induce 1,4-silyl C(sp 2 )→O migration, vinyl bromide with a catalytic amount of Pd(PPh 3 ) 4 for the CCR, and TBAF to remove the TMS group; tricomponent adduct 10a was produced in 56% yield.Convinced that this "one-flask" multicomponent protocol would hold considerable potential, in general, we initiated a program to unite Anion Relay Chemistry with the cross coupling tactic. We quickly recognized, as reported by Takeda et al. 4 for ortho-TMS benzyl alcohol, that the use of CuI, and in our case a mixture of HMPA and THF (1:1), is required to trigger the 1,4-Brook rearrangement. Towards this end, addition of n-BuLi to 10, followed by CuI/ HMPA:THF induced silyl migration. the presence of 3 mol % Pd(PPh 3 ) 4 in THF at room temperature then, led to a series of cross coupled adducts (10a-10h) with yields ranging from 50-67% (Table 1).Having established the initial scope of the combined ARC-II/Pd-mediated CCR protocol, we turned to the design, synthesis and evaluation of a new class of bifunctional vinyl silanes, with electrophilic sites β or γ to the silane (Figure 1), first to explore their utility as linchpins for the Type II ARC tactic and then as linchpins in the combined ARC-II/Pd-mediated CCR process.Linchpin 11 was readily available via oxidation of known alcohol 17, 5 while 12 was prepared from epoxide 18 6 and commercial vinyl bromide 19 (Scheme 3).To explore the ARC tactic with 11, we selected conditions that proved effective with 10. 3 As illustrated in Table 2, addition of n-BuLi in Et 2 O, followed by CuI (1.2 equiv) in a mixture of HMPA/THF (1:1), and then a variety of carbon-and heteroatom-based electrophiles furnished adducts 21a-21d in 63-68% yield. Under these conditions, the 1,4 silyl migration proceeded rapidly (ca. 30 min). Equally important, palladium-mediated cross coupling rea...