Synlett 2018; 29(15): 1944-1956
DOI: 10.1055/s-0037-1610022
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© Georg Thieme Verlag Stuttgart · New York

Proline-Catalyzed Asymmetric α-Amination in the Synthesis of Bioactive Molecules

Pradeep Kumar*
a   Organic Chemistry Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune-411008, India   Email: pk.tripathi@ncl.res.in
b   Academy of Scientific and Innovative Research (AcSIR), New Delhi 110025, India
,
Brijesh M. Sharma
a   Organic Chemistry Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune-411008, India   Email: pk.tripathi@ncl.res.in
b   Academy of Scientific and Innovative Research (AcSIR), New Delhi 110025, India
› Author Affiliations
B. M. S. thanks the Council of Scientific and Industrial Research (CSIR) for the award of a Senior Research Fellowship.
Moreover, the financial support in the form of INSA senior scientist program to P. K from INSA, New Delhi is gratefully acknowledged.
Further Information

Publication History

Received: 28 February 2018

Accepted after revision: 24 April 2018

Publication Date:
19 June 2018 (online)


Abstract

The direct α-amination of carbonyl compounds using organocatalysts represents a powerful and atom-economical tool for asymmetric C–N bond formation. We describe a complete account of α-functionalization of carbonyl compounds, through iterative sequential α-aminoxylation/amination using electrophilic O and N sources, as well as sequential α-amination/HWE reaction for enantio- and diastereoselective synthesis of both syn- and anti-1,3-aminoalcohols and 1,3-diamines. Additionally this protocol is further extended for the easy construction of alkaloids such as indolizidine, pyrrolizidine, and quinolizidine fused-ring systems just by tuning the chain length of the aldehyde used as a starting material. This methodology provides further scope to extrapolate it for a variety of naturally occurring hydroxylated monocyclic and fused bicyclic pyrrolidine and piperidine based alkaloids such as lentiginosine, epi-lentiginosine, dihydroxypyrrolizidine, (+)-deoxoprosophylline and (–)-deoxoprosopinine alkaloids. Furthermore, we have also uncovered proline-catalyzed anti-selectivity for the synthesis of 1,2-amino alcohols in α-amination of aldehyde and one-pot indium-mediated Barbier type allylation of α-hydrazino aldehydes to accomplish the total synthesis of clavaminols, sphinganine and spisulosine with reduced number of steps and with high overall yields.

1 Introduction

2 Application in the Total Synthesis of Alkaloids

3 Conclusion