Suzuki–Miyaura Cross-Coupling of 1,8-Diaminonaphthalene (dan)-Protected Arylboronic Acids

Abstract

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.

Fluorinated Aryl Boronates as Building Blocks in Organic Synthesis

“…introduced protected analogues of aryl boronates, namely aryl‐Bdan (dan = naphthalene‐1,8‐diaminato) derivatives, for which the C−B bond is less reactive due to the reduced Lewis acidity of the boron atom [129] . In 2020, Saito et al [130] . and Tsuchimoto et al [131] .…”

“…reported a method to apply aryl‐Bdan compounds in Suzuki‐Miyaura cross‐coupling reactions. Indeed, Saito et al [130] . reported examples of different polyfluorophenyl‐Bdan derivatives, especially C 6 F 5 Bdan, that were coupled without difficulty with aryl iodides using a combination of common palladium catalyst precursors such as [Pd 2 (dba) 3 ]⋅CHCl 3 and ligands such as XPhos.…”

“…showed that C 6 F 5 B(OH) 2 is susceptible to nucleophilic attack at its para ‐carbon atom to replace the para ‐fluoro‐substituent with potassium tert ‐butoxide (KO t ‐Bu) [132] . However, the method described by Saito et al [130] . above used excess strong base, such as a 1 M solution of KO t ‐Bu in THF, but, interestingly, attack at the para ‐carbon was not mentioned.…”

Pairing Suzuki–Miyaura cross-coupling and catalyst transfer polymerization

“…For the most part, these have only been used as protecting groups, though recent work has shown some of these derivatives can participate in coupling directly. 97,98 The trifluoroborate salts 99 (BF 3 K) have not yet been explored for chain-growth polymerizations, but these derivatives are typically compatible with environmentally friendly solvents such as water and alcohol. Pairing trifluoroborates with water-soluble conjugated polymers 100 could be an exciting new strategy to build polyaromatics in environmentally benign media.…”

Synthetic Chemistry with Lewis Acidity‐Diminished B(aam) and B(dan) Groups: Borylation Reactions and Direct Cross‐Couplings

“…Much more robust C( sp 2 )–B(dan) bonds of aryl– and alkenyl–B(dan)s, which are actually unreactive under the above alkynyl–B(dan)’s conditions, were recently demonstrated to undergo direct SMC by Yoshida–Tsuchimoto [44] (Scheme 53) and Mutoh–Saito [39,45] (Scheme 54) independently. The use of t ‐BuOK as a base under anhydrous conditions is the key to the smooth coupling, and the direct SMC allowed various 2‐pyridyl–B(dan)s to be efficiently transformable into the respective products.…”