An organocatalytic direct Mannich–cyclization cascade as [3+2] annulation: asymmetric synthesis of 2,3-substituted pyrrolidines
作者:Indresh Kumar、Nisar A. Mir、Vivek K. Gupta、Rajnikant
DOI:10.1039/c2cc33103a
日期:——
A new method for asymmetric synthesis of 2,3-substituted pyrrolidines from N-PMP aldimines and succinaldehyde via formal [3+2] cycloaddition is reported. This reaction involves proline catalyzed direct Mannich reaction and acid catalyzed reductive cyclization with high yields (up to 78%) and excellent enantioselectivities (up to >99%).
An Unprecedented Pseudo-[3+2] Annulation between <i>N</i>
-(4-Methoxyphenyl)aldimines and Aqueous Glutaraldehyde: Direct Synthesis of Pyrrole-2,4-dialdehydes
作者:Panduga Ramaraju、Nisar A. Mir、Deepika Singh、Preetika Sharma、Rajni Kant、Indresh Kumar
DOI:10.1002/ejoc.201700500
日期:2017.6.30
A new method for the direct one-pot synthesis of substituted pyrrole-2,4-dialdehdyes was developed. This overall pseudo-[3+2]-annulation reaction between glutaraldehyde and N-(4-methoxyphenyl)aldimines proceeds through proline-catalyzed direct Mannich reaction/cyclization, followed by 2-iodoxybenzoic acid mediated oxidative rearrangement of the in situ generated intermediate to give pyrrole-2,4-dialdehydes
Enantioselective Synthesis of <i>N</i>-PMP-1,2-dihydropyridines via Formal [4 + 2] Cycloaddition between Aqueous Glutaraldehyde and Imines
作者:Panduga Ramaraju、Nisar A. Mir、Deepika Singh、Vivek K. Gupta、Rajni Kant、Indresh Kumar
DOI:10.1021/acs.orglett.5b02744
日期:2015.11.20
A simple and highly practical one-pot formal [4 + 2] cycloaddition approach for the enantioselective synthesis of N-PMP-1,2-dihydropyridines (DHPs) is described. This chemistry involves an amino-catalytic direct Mannich reaction/cyclization followed by IBX-mediated chemo- and regioselective oxidation sequence between readily available aqueous glutaraldehyde and imines under very mild conditions. A
Direct catalytic synthesis of densely substituted 3-formylpyrroles from imines and 1,4-ketoaldehydes
作者:Indresh Kumar、Nisar A. Mir、Panduga Ramaraju、Deepika Singh、Vivek K. Gupta、Rajnikant Rajnikant
DOI:10.1039/c4ra06581f
日期:——
An organocatalytic formal [3 + 2] cycloaddition have been developed between 1,4-ketoaldehydes and imines to synthesize densely substituted 3-formylpyrroles in high yields (up to 70%) under mild conditions at room temperature.
Highly enantioselective [4+2] annulation via organocatalytic Mannich-reductive cyclization: one-pot synthesis of functionalized piperidines
作者:Indresh Kumar、Panduga Ramaraju、Nisar A. Mir、Deepika Singh、Vivek K. Gupta、Rajnikant
DOI:10.1039/c3cc42431f
日期:——
one-pot synthesis of 2,3-substituted piperidine from N-PMP aldimine and aqueous glutaraldehyde via formal [4+2] cycloaddition is reported. This reaction involves organocatalytic direct Mannich reaction-reductive cyclization with high yields (up to 90%) and excellent enantioselectivities (up to >99%). The practicability of this method is also shown at a gram scale as well as through the synthesis of functionalized