Synthesis 2021; 53(24): 4621-4635
DOI: 10.1055/a-1561-7815
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Development of a Chiral N-Alkoxyamide Strategy and Application to the Asymmetric Total Synthesis of Fasicularin

Ryo Minamikawa
a   Department of Applied Chemistry, Faculty of Science and Technology, Keio University, 3-14-1, Hiyoshi, Kohoku-ku, Yokohama, 223-8522, Japan
,
Keisuke Fukaya
b   Biotechnology Research Center and Department of Biotechnology,Toyama Prefectural University, 5180 Kurokawa, Imizu, Toyama, 939-0398, Japan
,
Akihiro Kobayashi
a   Department of Applied Chemistry, Faculty of Science and Technology, Keio University, 3-14-1, Hiyoshi, Kohoku-ku, Yokohama, 223-8522, Japan
,
Yukinori Komiya
a   Department of Applied Chemistry, Faculty of Science and Technology, Keio University, 3-14-1, Hiyoshi, Kohoku-ku, Yokohama, 223-8522, Japan
,
Shio Yamamoto
a   Department of Applied Chemistry, Faculty of Science and Technology, Keio University, 3-14-1, Hiyoshi, Kohoku-ku, Yokohama, 223-8522, Japan
,
Daisuke Urabe
b   Biotechnology Research Center and Department of Biotechnology,Toyama Prefectural University, 5180 Kurokawa, Imizu, Toyama, 939-0398, Japan
,
Noritaka Chida
a   Department of Applied Chemistry, Faculty of Science and Technology, Keio University, 3-14-1, Hiyoshi, Kohoku-ku, Yokohama, 223-8522, Japan
,
Takaaki Sato
a   Department of Applied Chemistry, Faculty of Science and Technology, Keio University, 3-14-1, Hiyoshi, Kohoku-ku, Yokohama, 223-8522, Japan
› Author Affiliations
This research was supported by a Grant-in-Aid for Scientific Research (C) from the Ministry of Education, Culture, Sports, Science and Technology (MEXT, 15K05436), the TOBE MAKI Scholarship Foundation, and the JGC-S Scholarship Foundation.


Abstract

The asymmetric total synthesis of fasicularin by a chiral N-alkoxyamide strategy is reported. Incorporation of the chiral alkoxy group onto an amide nitrogen changes the original reactivity of the amide, enabling two key transformations: aza-spirocyclization and the reductive Strecker reaction. DFT calculations indicate that pyramidalization of the N-alkoxyamide nitrogen is crucial to produce a cyclic hemiaminal in equilibrium, which undergoes aza-spirocyclization. The chiral alkoxy group is also used as a stereocontrol element to establish two consecutive stereocenters. The iridium-catalyzed reductive Strecker reaction of the N-alkoxylactam provides the aminonitrile with high diastereoselectivity.

Supporting Information



Publication History

Received: 30 June 2021

Accepted after revision: 29 July 2021

Accepted Manuscript online:
29 July 2021

Article published online:
17 September 2021

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