A cascade cyclization involving union of three imines by an organocatalyst proline is established to afford new fused-tetrahydroimidazo[1,5-c]imidazol-7- ones with excellent regio- and stereoselectivity. Another dehydrogenative cyclization by union of two imines is developed using the Cu(OTf) 2-Ag 2O combo catalyst to furnish functionalized imidazoles. © 2012 The Royal Society of Chemistry.

DILIP MAITI

Chemistry

Y SAIMA

S KHAMARUI

K S GAYEN

P PANDIT

University of Calcutta (informally known as Calcutta University or CU) is a collegiate public state university located in Kolkata, West Bengal, India.&nbsp;Within India it is recognized as a &quot;Five-Star University&quot; and accredited &quot;A&quot; Grade by National Assessment and Accreditation Council.

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The University of Calcutta has secured the Fifth position among the Universities of India in the prestigious &quot;Indian University Ranking 2019&quot; list, released by the NIRF of the Ministry of Human Resource Development, Government of India.

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It was established on 24 January 1857, and was one of the first institutions in Asia to be established as a multidisciplinary and Western-style university. Its alumni and faculty include several heads of state, heads of government, social reformers, prominent artists, only academy award winner and Dirac medal winner in India, many Fellows of the Royal Society and five Nobel laureates as of 2019 which is highest in South Asia.

University Of Calcutta

Chemical Communications

We discover an important property of a small molecule ArCH(OMe)2 which transforms catalytically inactive PtIIBr2 procatalyst in situ to an powerful catalyst PtIV-species for diverse annulation reaction. The powerful catalytic system enables selective activation of C2-H/N-H and C2-H/C4-H of acetoacetanilide and C5O/C;C of substituted butyne-1,2-dione for C-C/C-N, C-C/C-C and C-O/C-O bond-forming inter- and intramolecular annulation towards direct syntheses of functionalised 2-pyridones, cyclohexenones and 3(2H)-furanones respectively. In contrast to the common ligand, herein highly labile C-OMe bond of ArCH(OMe)2 is expected to react with PtBr2 towards generation of the high-valent active catalyst. Unlike catalyst promoter or initiator, the reaction does not occur with PtBr2 in the absence of ArCH(OMe)2. In situ generation of PtIV-species and -OMe fragment of ArCH(OMe)2 were confirmed from the UV-vis characteristic peaks about 260 nm and trapping of -OMe group respectively. These observations provide new prospects and perspectives in catalysis for innovative catalyst design.

Fulltext

Scientific Reports

ArCH(OMe)2-A PtIV-catalyst originator for diverse annulation catalysis

CHEMISTRY-A EUROPEAN JOURNAL

FeCl3 center dot 6H2O-Catalyzed Intermolecular-Cascade Cyclization of Acetoacetanilide: Aldehyde-Tuned Synthesis to Valuable 2-Pyridone Analogues

Intramolecular formal 1,3-dipolar cycloaddition of ketoimine is developed with PhIO for the first synthesis of fused-Δ1-pyrrolines. The scope of the reaction, complete diastereoselectivity and its rationalization by a computational study are reported. © 2011 The Royal Society of Chemistry.

First synthesis of fused-Î”1-pyrrolines via intramolecular 1,3-dipolar cycloaddition of ketoimine: A complete diastereoselective approach

Synfacts

Synthesis of Quinolines through Double-Oxidative Dehydrogenative Cyclization

Journal of Medicinal Chemistry

Discovery of Imidazo[1,5-c]imidazol-3-ones: Weakly Basic, Orally Active Factor Xa Inhibitors

Chemical Society Reviews

Supported proline and proline-derivatives as recyclable organocatalysts

Efficient catalytic cyclizations of three and two imine assemblies: Direct access to tetrahydroimidazo[1,5-c]imidazol-7-ones and imidazoles

Journal	Chemical Communications
Publisher	ROYAL SOC CHEMISTRY
ISSN	1359-7345