%0 Journal Article %A Krow, Grant R. %A Herzon, Seth B. %A Lin, Guoliang %A Qiu, Feng %A Sonnet, Philip E. %D 2002 %T Complex-Induced Proximity Effects. Temperature-Dependent Regiochemical Diversity in Lithiation−Electrophilic Substitution Reactions of N-BOC-2-Azabicyclo[2.1.1]hexane. 2,4- and 3,5-Methanoprolines %U 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/3743784 %R 10.1021/ol026509b.s001 %2 https://acs.figshare.com/ndownloader/files/5837148 %K regioisomeric methylene %K mixture %K DMF %K aldehyde 8 c %K bridgehead acids 6 %K bridgehead acid 8 %K anion %K quenching %K BOC methyl ester 6 b %X Azabicycle 4 and sec-butyllithium/TMEDA afford the C1 bridgehead α-lithio anion at 0 °C. Anion quenching with carbon dioxide, methyl chloroformate, or DMF provide the bridgehead acid 8a (N-BOC-2,4-methanoproline), ester 8b, or aldehyde 8c, 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 6a/8a, esters 6b/8b, or aldehydes 6c/8c, respectively. The previously unknown 3,5-methanoproline was prepared as its N-BOC methyl ester 6b. %I ACS Publications