By using aldehydes or ketones as the catalyst and screening CsOH out as the more effective base than KOH in many instances, an efficient 9-C-alkylation of fluorenes with alcohols was...
central goal in catalysis. This would be especially interesting when the reactivity and selectivity patterns can be tuned. Herein, we introduced the first Mn-catalyzed selective C-alkylation and olefination of fluorene, and indene with alcohols. Various substrates including benzylic, heteroaromatic, and aliphatic primary and secondary alcohols are employed as alkylating agents. Mechanistic investigations
Asymmetrical dyes with large two-photon absorption cross-sections
申请人:The United States of America as represented by the Secretary of the Air
公开号:US05770737A1
公开(公告)日:1998-06-23
A two-photon absorbing chromophore of the formula D--Ar--A wherein Ar is selected from the group consisting of ##STR1## D is selected from the group consisting of ##STR2## and A is selected from the group consisting of ##STR3## wherein R.sub.1 and R.sub.2 are alkyl groups having 8 to 12 carbon atoms, and wherein R.sub.1 and R.sub.2 are the same or different.
Herein, we described the selective synthesis of both alkylated and alkenylated fluorenes using a single SNS ligand derived nickel complex. The protocol was employed for a wide range of substrates, including substituted fluorenes and various alcohols including aliphaticalcohols with a distal double bond. To expand the synthetic utility, an antimalarial drug analogue, benflumetol, was synthesized, and
Zn(II)‐Stabilized Azo‐Anion Radical Catalyzed Sustainable C−C Bond Formation: Regioselective Alkylation of Fluorene, Oxindole, and Indoles
作者:Subhasree Pal、Amit Kumar Guin、Subhajit Chakraborty、Nanda D. Paul
DOI:10.1002/cctc.202400026
日期:2024.5.21
Herein we report a sustainable approach for the alkylation of ketones, 9H‐fluorene, oxindole, and indole using alcohols as the alkylating agent catalyzed by a well‐defined air‐stable zinc catalyst (1 a) of a tridentate redox non‐innocent arylazo ligand, 2‐((4‐chlorophenyl)diazenyl)‐1,10‐phenanthroline (La). 2–3 mol % of 1 a efficiently produces substituted α‐alkylated ketones, 9‐alkylated fluorenes, C3‐alkylated oxindoles, and C3‐alkylated indoles in moderate to good isolated yields. In aerial condition, the formation of bis(indolyl)methane (BIMs) derivatives were observed when indoles were subjected to alkylation by primary alcohols. A few drug molecules containing BIMs were prepared in good isolated yields. The catalyst 1 a exhibited good chemoselectivity during the functionalization of fluorene and indole with oleyl alcohol and β‐citronellol. A few control experiments, including deuterium labeling experiments, performed to unveil the reaction mechanism indicate that the one‐electron reduced azo‐anion radical species [1 a]‐formed in situ, acts as the active catalyst. All the redox events occur at the redox‐active aryl‐azo ligand, which acts as the reservoir of hydrogen and electrons throughout the catalytic cycle, keeping the Zn(II)‐center as a template.