{'fraction_non_alphanumeric': 0.017418032786885244, 'fraction_numerical': 0.0010245901639344263, 'mean_word_length': 6.515384615384615, '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}}
Construction of Vicinal Quaternary Centers via Iridium-Catalyzed Asymmetric Allenylic Alkylation of Racemic Tertiary Alcohols.

Enantioselective bond formation between sterically hindered fragments to furnish acyclic products with vicinal quaternary centers is a formidable challenge. We report a solution that involves cocatalysis between a chiral Ir-(phosphoramidite,olefin) complex and La(OTf)3. This robust catalytic system effects highly enantioconvergent and regioselective alkylation of racemic tertiary α-allenyl alcohols with tetrasubstituted silyl ketene acetals. The transformation displays broad functional group tolerance for both reaction components and allows efficient generation of β-allenyl ester products in good yield and with excellent enantioselectivity. Furthermore, both the allene and ester functionalities were leveraged to upgrade the structural complexity of the products via a series of stereoselective metal-catalyzed functionalization reactions.