Sreekumar, Krishnapillai; Rajesh Krishnan, G(Eur. J. Org. Chem, August , 2008)
[+]
[-]
Abstract:
This paper describes the first use of polystyrene-supported
poly(amidoamine) (PAMAM) dendrimers as heterogeneous
basic organocatalysts for carbon–carbon bond formation.
Polystyrene-supported PAMAM dendrimers of first, second
and third generations have been used as reusable base catalysts
in Knoevenagel condensations of carbonyl compounds
with active methylene compounds. The reactions proceed in short periods of time and with 100% selectivity. This novel
catalyst eliminates the use of aromatic and halogenated solvents,
as well as complex purification processes. The catalysts
can be recycled ten times.
Siji,Thomas; Vijay Nair,G(ORGANIC CHEMISTRY DIVISION REGIONAL RESEARCH LABORATORY (CSIR), December , 2004)
[+]
[-]
Abstract:
A systematic investigation of the reactivity and functionalization of two
heterocyclic analogs of triphenylmethane , namely tris(2-thienyl)methane and
tris(2-furyl)methane have been carried out and the results are presented in this
thesis entitled "NOVEL REACTIONS OF TRIS(2-THIENYL)METHANE AND
TRIS(2-FURYL)METHANE.". The history of organic free radicals dates back to Gomberg's monumental discovery of the triphenylmethyl radical in 1900. The heterocyclic analogs of triarylmethane are also interesting from the vantage point of their transformation to the corresponding radicals akin to Gomberg ' s triphenylmethyl radical and also they are prone to further transformation leading to three dimensionally elongated molecules such as dendrimers. Dendritic architectures are one of the most pervasive topologies observed in nature at the macro- and microdimensional length devices. Because of their ability to combine both organic and inorganic compounds and their propensity to either encapsulate or be engineered into unimolecular functional devices , dendrimers are versatile amongst existing nanoscale building blocks and materials.