Marcella Bosco

The reaction of vinyl grignard reagents with 2-substituted nitroarenes: A new approach to the synthesis of 7-substituted indoles

Abstract The reaction of three moles of vinylmagnesium bromide with one mole of nitroarene leads to the formation of indoles after aqueous work up of the mixture. Good yields are obtained with ortho -substituted nitroarenes.

Organocatalytic asymmetric hydrophosphination of nitroalkenes

The use of a bifunctional Cinchona alkaloid catalyst has provided a new organocatalytic strategy for the enantioselective addition of diphenylphosphine to a range of nitroalkenes, affording optically active beta-nitrophosphines (up to 99% ee after crystallization); this organocatalytic approach, providing a direct route to a new class of potentially useful enantiopure P,N-ligands, constitutes a bridge between the two complementary areas of asymmetric catalysis: organo- and metal-catalyzed transformations.

Cerium(III) Chloride Catalyzed Michael Reaction of 1,3-Dicarbonyl Compounds and Enones in the Presence of Sodium Iodide Under Solvent-Free Conditions

Cerium(III) chloride heptahydrate in the presence of sodium iodide catalyses the Michael addition of 1,3-dicarbonyl compounds to α,β-unsaturated ketones and α,β-unsaturated aldehydes with extraordinary efficiency. The very mild conditions allow high chemoselectivity as shown by the absence of the typical side reactions, which can be observed in the conventional base-catalyzed processes. More interestingly, when at least one of the starting materials is liquid at room temperature, the reaction can also be performed without solvents. The CeCl3· 7 H2O/NaI catalyst system can be easily separated from the reaction mixture and it can be reused without an appreciable loss of activity. Advantages of the present procedure, which utilizes cheap and “friendly” reagents, over the previously reported ones, are discussed.

LiClO4-acyl anhydrides complexes as powerful acylating reagents of aromatic compounds in solvent free conditions

Abstract The Friedel–Crafts acylation of various activated benzenes is smoothly carried out with acyl anhydrides in the presence of 2 equiv. of LiClO 4 , as reaction promoter, under solventless conditions.

Unexpected reactivity of allyl magnesium chloride with nitroarenes. A general method of synthesis of N-allyl-N-arylhydroxylamines and N-allylanilines

Abstract In contrast to alkyl Grignard reagents, the allyl reagent reacts with nitroarenes via 1,2 addition to the nitro group. The “in situ” treatment of the unstable intermediate adduct with LiAlH 4 in the presence of catalytic Pd/C provides a general synthesis of N-allyl-N-arylhydroxylamines or N-allylanilines.

Cerium(III) chloride mediated Michael addition of RMgX to nitroenes: a very efficient access to complex nitroalkanes.

Abstract Reactions of RMgXCeCl3 complexes with nitroenes lead to functionalized nitroalkanes in very good yields.

Unexpected elimination to α,β-alkynylketones in the reaction of dianions of 1-arylenaminones with trimethylchlorosilane

Abstract Alkynylketones were obtained in good yield from reaction of 3-( N -isopropylamino)-1-arylbut-2-en-1-ones with chlorotrimethylsilane. On the other hand, t -butyldimethylchlorosilane leads to γ-silylated enaminones. Compounds arising from silicon attack at the oxigen atom are never observed. Evidence of the mechanistic pathway of the reaction are reported.

TiCl4 Mediated LiBH4 reduction of β-ketophosphine oxides: a high stereoselective route to the synthesis of anti-β-hydroxyphosphine oxides

The reduction of an α-alkyl-β-ketophosphine oxide with LiBH4 in presence of a strong chelating agent, such as TiCl4, gives the corresponding β-hydroxyphosphine oxide in high yields and with high anti-diastereoselectivity independently from the size of both the α- and β-alkyl chains.

Reaction of dianion β-enamino ketones with electrophiles. Part 4. Synthesis of β′- and δ-hydroxy-β-enamino ketones.

Abstract Selective generation techniques of α′ and γ dianions of β-enamino ketones allow an almost complete regiocontrol in the reaction with aldehydes and ketones for the synthesis of β′-and δ-hydroxy-β-enamino ketones. An important role is also displayed by bulkiness of the substituent at the nitrogen atom. The reaction gives good to high yields even with enolizable carbonylic compounds. α,β-insaturated aldehydes and ketones generally undergo 1,2-addition process except in the case of high sterically hindered compounds.

Alkylatlon orientation rules in conjugate addition of grignard reagents to nitropyrrole and nitrothiophene systems

Abstract Conjugate addition of various Grignard reagents to 1-alkyl-2-nitropyrroles and to 2-nitrothiophene has been investigated. 1-Alkyl-2-nitropyrroles undergo alkylation at 3 and 5 positions with prevalence of the latter isomer. On the contrary, in 2-nitrothiophene system, formation of the 3-isomer prevails. In both systems, a bulkier Grignard reagent favours the 5-isomer formation. This trend can be reversed increasing steric hindrance exerted by the 1-substituent of 2-nitropyrrole. 1-(Tri-isopropylsilyl)-3-nitropyrrole and 3-nitrothiophene give exclusively the 2-isomer. This rection allows 2-alkyl-3-nitrothiophenes and pyrroles to be synthesized with a one-pot procedure instead of the classical multi-stage reaction.