b
Department of Chemical Sciences, Indian Institute of Science Education and Research Bhopal, Bhauri, Bhopal 462 066, Madhya Pradesh, India
d
Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, Nadia 741 246, West Bengal, India
› Author AffiliationsPartial financial support from the Science and Engineering Research Board (SERB; CRG/2023/000782, SCP/2022/000486), the Ministry of Education, India [STARS, MoE (2023/000753)], and the Council of Scientific and Industrial Research, India [CSIR, 02(0295)/17/EMR-II] is gratefully acknowledged. A.B. is a SERB-STAR Fellow and sincerely acknowledges the SERB (STR/2020/000061) for generous support. M.K.D. and S.C. thank the CSIR and University Grants Commission, respectively, for senior research fellowships. K.S. thanks the Indian Institute of Science Education and Research Bhopal for a predoctoral fellowship.
This work is dedicated respectfully to Prof. H. Ila, JNCASR Bangalore, India.
Abstract
An efficient asymmetric approach to the ergot alkaloids has been achieved via a highly regioselective Heck cyclization. Asymmetric induction of the key intermediate was achieved via a catalytic enantioselective α-aminoxylation catalyzed by d-proline (98% ee). Utilizing the aforementioned strategy, formal total synthesis of the ergot alkaloids (+)-lysergine and (+)-isolysergine has been achieved. Importantly, an asymmetric approach to the unnatural analogues (–)-lysergine and (–)-isolysergine has also been achieved via catalytic enantioselective α-aminoxylation using l-proline.
6a
Jakubczyk D,
Caputi L,
Hatsch A,
Nielson CA. F,
Diefenbacher M,
Klein J,
Molt A,
Schröder H,
Cheng JZ,
Naesby M,
O’Conner SE.
Angew. Chem. Int. Ed. 2015; 54: 5117
9a For utilization of an α-aminoxylation reaction in the total synthesis of (+)-cycloclavine, see:
Chaudhuri S,
Ghosh S,
Bhunia S,
Bisai A.
Chem. Commun. 2018; 54: 940
13 Mitsunobu reaction of δ-amino alcohols 18a, 18b using diethyl azodicarboxylate (DEAD) and PPh3 in toluene yielded compounds 20a, 20b in 56–59% isolated yield.
14
Lu Y,
Yuan H,
Zhou S,
Luo T.
Org. Lett. 2017; 19: 620