B. Gopalan

Bio: B. Gopalan is an academic researcher from University of Madras. The author has contributed to research in topics: Claisen rearrangement & Ene reaction. The author has an hindex of 4, co-authored 5 publications receiving 33 citations.

Part I: Nitroalkenes in the synthesis of heterocyclic compounds

Abstract: The applications of nitroalkenes in the synthesis of three- to five-membered O, N and S-heterocycles, including natural products are investigated in this review. These heterocyclic compounds were synthesized from nitroalkenes with a variety of substituents at the α and β-positions and those that were part of common and medium rings via a wide variety of reactions such as Michael addition reactions, epoxidation, [3 + 2] cycloaddition and many cascade/domino/tandem reactions. In addition, the potential of nitroalkenes to take part in multi-component and cascade reactions, particularly, in diastereo- and enantioselective versions is reviewed. The high reactivity of nitroalkenes and their potential to coordinate with the metal catalysts as well as organocatalysts signify them as efficient precursors in synthetic organic chemistry. Also, the flexibility of the nitro group in functional group manipulations has expanded the scope of the nitro group, in general, and nitroalkenes, in particular, in organic synthesis.

The Catalyzed α‐Hydroxyalkylation and α‐Aminoalkylation of Activated Olefins (The Morita—Baylis—Hillman Reaction)

Abstract: In a patent application published in 1972, Baylis and Hillman reported the reaction of acetaldehyde with ethyl acrylate and acrylonitrile in the presence of catalytic amounts of 1,4-diazabicyclo[2.2.2]octane to give the α-hydroxyethylated products in good yields. No structure proof was given. The assignment eventually was shown to be correct, but since the initial disclosure was not followed by a journal publication, this remarkably simple, atom-efficient, and useful reaction was ignored for a number of years, and it has been only fairly recently that its potential has begun to be explored. The transformation is now commonly referred to as the Baylis–Hillman reaction. This is unfortunate because credit for its invention clearly belongs to Morita, who five years earlier, in patents and a brief paper reported the same reaction with the exception that tertiary phosphines were used as the catalysts; he also proposed the currently accepted mechanism. Baylis and Hillman made reference to Morita's work in their patent application. It is true that tertiary amines in general are cheaper, less toxic, and more readily removed than tertiary phosphines. However, the latter sometimes give higher yields in shorter reaction times, and there are a number of examples where they are the only useful catalysts. The DABCO-catalyzed reaction is slow, and reaction times at room temperature of days or even weeks are common. Attempts to remedy this situation by use of other amine catalysts, change of reaction temperature, high pressure, or microwave irradiation have been partially successful. Activated olefins other than acrylonitrile and acrylic esters that have now been shown to undergo the reaction include α,β-unsaturated aldehydes and ketones, vinyl sulfoxides, vinyl sulfones, vinylsulfonates, and vinylphosphonates. β-Substituted activated olefins do not normally react. Among electrophiles other than aldehydes, unactivated ketones undergo the Morita–Baylis–Hillman reaction only under high pressure, but activation such as in α-halo ketones, α-keto esters, α-keto lactones, and nonenolizable α-diketones often produces very reactive substrates. Imines also can be employed, provided they carry a sufficiently electronegative group on nitrogen. This chapter covers catalyzed α-hydroxyalkylations and α-aminoalkylations of activated olefins. Transition metal catalyzed reactions of this type, are also included even though they proceed by a different mechanism. Transformations that require stoichiometric amounts of reagents or more than one step are summarized in the section on Comparison With Other Methods but are not included in the Tabular Survey. The Morita–Baylis–Hillman reaction has been reviewed before. Keywords: catalysts; hydroxyalklyation; aminoalkylation; activated olefin; acrylates; allenic esters; acrylamides; acrylonitrile; acrolein; unsaturated ketones; vinyl sulfoxides; vinyl sulfones; vinylsulfonates; vinylphosphonates; substituted activated olefins; electrophile; intramolecular reactions; side reactions; aldehydes; diketones; keto esters; keto lactones; imines; iminium salts; Aldol and Michael reactions; Morita-Baylis-Hillman reaction; comparison of methods; synthetic utility; experimental conditions; experimental procedures; tabular survey

Compositions of protein receptor tyrosine kinase inhibitors

Abstract: The present invention relates to novel synthetic substituted heterocyclic compounds and pharmaceutical compositions containing the same that are capable of inhibiting or antagonizing a family of receptor tyrosine kinases, Tropomysosin Related Kinases (Trk), in particular the nerve growth factor (NGF) receptor, TrkA. The invention further concerns the use of such compounds in the treatment and/or prevention of pain, cancer, restenosis, atherosclerosis, psoriasis, thrombosis, or a disease, disorder or injury relating to dysmyelination or demyelination or the disease or disorder associated with abnormal activities of NGF recptor TrkA.