Anthranilamide (AAM)-masked o-iodoarylboronic acids were prepared from AAM-masked arylboronic acids via Rucatalyzed o-CH silylation, followed by iododesilylation with ICl. The SuzukiMiyaura coupling of AAM-masked o-haloarylboronic acids with arylboronic acids proceeded under ligandfree conditions. Oligo(o-phenylene)s and oligo(naphthalene-2,3-diyl)s were synthesized via iterative SuzukiMiyaura coupling sequences.Interest in the synthesis and structure of ortho-linked oligoarenes and hetarenes has been increasing.14 They cannot adopt planar structure, but they form helical structures due to the steric repulsion of the substituents on the aromatic rings. In addition to their static helical structures, the dynamic change in the helical structures has attracted increasing attention from the viewpoint of application to functional materials.5 For instance, we have recently established solvent-dependent, reversible switch of helical conformation of poly(quinoxaline-2,3-diyl)s with high molecular weight. 6 This system was successfully applied to a new chiral catalyst system in which either enantiomer can be produced with high enantioselectivity from a single chiral catalyst.7 Although attractive, ortho-linked oligoarenes and hetarenes have not been explored in detail yet, mainly because of paucity of robust synthetic approaches. Therefore, it is highly desirable to establish general, efficient synthetic methods that would also allow the synthesis of functionalized oligoarenes in a sequence-selective manner.We have been interested in the development of crosscoupling-based organic synthesis, including iterative synthesis of oligoarene derivatives on the basis of boron-masking strategy using 1,8-diaminonaphthalene (DAN) as a highly effective masking group. 8 We subsequently established a removable ortho-directing group (o-DG), which is attached to the boron atom of the boronyl group and allows Ru-catalyzed o-silylation.

Tartrate-derived (2R,3R)-1,4-dimethoxy-1,1,4,4-tetraphenylbutane-2,3-diol has found diverse applications in asymmetric organic synthesis. Among these, its utilization as a protecting group for boronic acids has been investigated extensively. Besides being extraordinarily stable and thus allowing a plethora of transformations, it enables access to various diastereo- and enantiomerically pure organoboron reagents and versatile intermediates in asymmetric synthesis.

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