{'fraction_non_alphanumeric': 0.027777777777777776, 'fraction_numerical': 0.009259259259259259, 'mean_word_length': 6.213333333333333, '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}}
Synthesis of oxepanes and trans-fused bisoxepanes via biomimetic, endo-regioselective tandem oxacyclizations of polyepoxides.

[reaction: see text] This communication describes the first examples of tandem endo-regioselective and stereospecific oxacyclizations of 1, 5-diepoxides to oxepane products and a similar tandem oxacyclization of 1,5,9-triepoxides to fused bisoxepane cyclic carbonates. A mechanism for these biomimetic oxacyclizations is proposed in which the epoxides act as both electrophilic and nucleophilic reaction partners.