{'fraction_non_alphanumeric': 0.02230843840931135, 'fraction_numerical': 0.0, 'mean_word_length': 5.926174496644295, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Origins of Internal Regioselectivity in Copper-Catalyzed Borylation of Terminal Alkynes

Installation of a boron functionality into a more substituted carbon of terminal alkynes has been a challenging issue in chemical synthesis, since inherently Lewis acidic boron moieties, in principle, favor their attachment to a terminal carbon. Herein, we report on the highly internal-selective borylation of terminal alkynes under copper catalysis, wherein diminishment of boron-Lewis acidity and ligand-derived steric bulk around a copper center are the key to the success. In particular, the use of an anthranilamide-substituted boron moiety [B(aam)] is of high synthetic significance, because its properly diminished Lewis acidity enabled the internal regioselectivity and the Suzuki–Miyaura cross-coupling activity to be compatibly achieved. This method provided direct and universal approach to variously substituted branched alkenylboron compounds, regardless of electronic and steric properties of a substituent on terminal alkynes.