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. Author manuscript; available in PMC: 2018 Nov 8.
Published in final edited form as: J Am Chem Soc. 2017 Oct 24;139(44):15868–15877. doi: 10.1021/jacs.7b08749

Scheme 2. Enantioselective Synthesis of Iodo Pyrrolizidinone (+)-21a.

Scheme 2

aReagents and conditions: (a) (±)-29 (1.0 equiv), EDCI (1.5 equiv), HOAt (1.0 equiv), (−)-34d (0.6 equiv), i-Pr2NEt (3.0 equiv), CH2Cl2, 0°C, 48 h, 75% based on 34d, 45% based on (±)-29; (b) I(sym-collidine)2ClO4 (5.0 equiv), CH2Cl2:MeOH:H2O 1:1:0.05 (v/v/v), 25 °C, 72 h, 47% (73% brsm); (c) I2 (3.0 equiv), NaHCO3 aq:Et2O 1:1 (v/v), 25 °C, 24 h, 74%.