We report a Suzuki−Miyaura cross-coupling reaction of 1,8-diaminonaphthalene (dan)-protected arylboronic acids in the presence of KOt-Bu, which does not require the removal of the dan moiety. Notably, the use of aryl-B(dan) in the Suzuki−Miyaura reaction provides a complementary solution to the protodeboronation problems. The base KOt-Bu plays a crucial role for the promotion of these cross-coupling reactions as it enables the formation of a borate salt. This reaction protocol was extended to the one-pot sequential Suzuki−Miyaura cross-coupling reaction of 4-[(pin)B]C 6 H 4 −B(dan), wherein the "less reactive" aryl-B(dan) moiety was cross-coupled preferentially.

The metal-catalyzed (Z)-selective hydroboration of terminal alkynes is synthetically challenging due to the usually (E)-selective nature of the hydroboration and the formation of the thermodynamically unstable (Z)-isomer. Herein, we report that N-heterocyclic-carbene-ligated ruthenium complexes catalyze the (Z)-selective hydroboration of terminal alkynes with H–B­(dan) (dan = naphthalene-1,8-diaminato), which generates a diverse range of synthetically valuable (Z)-alkenylboranes. Mechanistic studies, particularly the isolation of a catalytically relevant borylruthenium complex, revealed a mechanism that involves the insertion of the alkyne into a Ru–B bond, which provides a catalytic cycle that is distinctly different from that of previously reported (Z)-selective hydroborations. The direct cross-coupling of the obtained (Z)-alkenyl-B­(dan) enables the rapid synthesis of biologically active Combretastatin A-4 analogues.

Metal-catalyzed trans-1,2-hydrosilylations and hydroborations of terminal alkynes that generate synthetically valuable (Z)-alkenylsilanes and (Z)-alkenylboranes remain challenging due to the (E)-selective nature of the reactions and the formation of the thermodynamically unfavorable (Z)-isomer. The development of new, efficient catalytic systems for the (Z)-selective hydrosilylation and hydroboration of terminal alkynes is thus highly desirable from a fundamental perspective as it would deepen our understanding of the metal-catalyzed (Z)selective hydrosilylation and hydroboration of terminal alkynes. This personal account describes our research for developing a ruthenium complex that can efficiently catalyze the hydrosilylation and hydroboration of terminal alkynes, and for exploring the factors controlling (Z)-selectivity of the reactions. Our effort into the activation of B-protected boronic acids, RÀ B(dan) (dan = naphthalene-1,8-diaminato), that was believed not to participate in Suzuki-Miyaura crosscoupling, is also discussed.

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