Krow, Grant R. Herzon, Seth B. Lin, Guoliang Qiu, Feng Sonnet, Philip E. Complex-Induced Proximity Effects. Temperature-Dependent Regiochemical Diversity in Lithiation−Electrophilic Substitution Reactions of <i>N</i>-BOC-2-Azabicyclo[2.1.1]hexane. 2,4- and 3,5-Methanoprolines Azabicycle <b>4</b> and <i>sec</i>-butyllithium/TMEDA afford the C<sub>1</sub> bridgehead α-lithio anion at 0 °C. Anion quenching with carbon dioxide, methyl chloroformate, or DMF provide the bridgehead acid <b>8a</b> (<i>N</i>-BOC-2,4-methanoproline), ester <b>8b</b>, or aldehyde <b>8c</b>, respectively. By contrast, at −78 °C these same reagents give a mixture of regioisomeric methylene and bridgehead anions whose quenching leads to mixtures of regioisomeric methylene and bridgehead acids <b>6a</b>/<b>8a</b>, esters <b>6b</b>/<b>8b</b>, or aldehydes <b>6c</b>/<b>8c</b>, respectively. The previously unknown 3,5-methanoproline was prepared as its <i>N</i>-BOC methyl ester <b>6b</b>. regioisomeric methylene;mixture;DMF;aldehyde 8 c;bridgehead acids 6;bridgehead acid 8;anion;quenching;BOC methyl ester 6 b 2002-08-14
    https://acs.figshare.com/articles/journal_contribution/Complex-Induced_Proximity_Effects_Temperature-Dependent_Regiochemical_Diversity_in_Lithiation_Electrophilic_Substitution_Reactions_of_i_N_i_-BOC-2-Azabicyclo_2_1_1_hexane_2_4-_and_3_5-Methanoprolines/3743787
10.1021/ol026509b.s002