Iodine-catalyzed allylation of 1,3-dicarbonyl compounds with allylic alcohols at room temperature

Methyltrifluoromethanesulfonate Catalyst in Direct Nucleophilic Substitution of Alcohols; One-Pot Synthesis of 4H-Chromene Derivatives

The catalytic activity of methyltrifluoromethanesulfonate (MeOTf) has been explored toward direct nucleophilic substitution of the hydroxyl group of nonmanipulated alcohols such as benzylic, allylic, propargylic, and tertiary alcohols with a wide range of uncharged nucleophiles such as 1,3-dicarbonyl compounds, amides, alkynes, and indoles to generate functionalized 1,3-dicarbonyl compounds, amides, alkynes, and indoles, respectively. Thus, the present protocol defines an alternate pathway to construct new C-C, C-N, and C-O bonds with the formation of water as the byproduct under mild conditions without any acids or metals. A completely different mechanism was established through several control experiments to explain the reaction methodology. As an application of the reported protocol, 1H-indene derivatives have been synthesized in one pot when benzylic alcohols were subjected to react with internal alkynes. The scope of the reaction has been further extended toward a tandem benzylation-cyclization-dehydration of 1,3-dicarbonyl compounds with 2-hydroxybenzyl alcohols, which furnish biologically important 4H-chromene derivatives.

Molecular Iodine-Catalyzed N-Benzylic Sulfonamides C-N Bond Cleavage for the Decarboxylative Substitution of β-Keto Acids

Abstract:

A molecular iodine-catalyzed system for the decarboxylative substitution reactions of β-keto acids with N-benzylic sulfonamides via sp3 C-N bond cleavage has been disclosed. This procedure provides a series of α-functionalized ketones in good to excellent yields. Furthermore, the practicability of this method could be manifested efficiently in a gram-scale synthesis.

Boron-catalyzed dehydrative allylation of 1,3-diketones and β-ketone esters with 1,3-diarylallyl alcohols in water

A metal-free catalytic allylation with atom economy and green environment friendly was developed. Allylic alcohols could be directly dehydrated in water by B(C6F5)3, without using any base additives. The reaction can afford the corresponding monoallylated product in moderate to high yield and has been performed on a gram-scale, and a quaternary carbon center can be constructed for the active methine compounds of 1,3-diketones or β-ketone esters in this process. The product can be further converted, such as the synthesis of tetra-substituted pyrazole compounds, or 1,4-dienes and functionalized dihydropyrans.

Transition metal-free decarboxylative alkylation reactions

This review summarizes recent advances in the transition metal-free decarboxylative alkylation of carboxylic acids and their derivatives.

Decarboxylative substitution of β-keto acids to benzylic alcohols catalyzed by molecular iodine

An efficient method for molecular iodine catalyzed decarboxylative substitution of β-keto acids with benzylic alcohols has been described.

Highly Efficient, One-Pot, Solvent-Free Synthesis of Highly Substituted Imidazoles Using Molecular Iodine as Catalyst

Highly efficient, one-pot synthesis of 2,4,5-trisubstituted and 1,2,4,5-tetrasubstituted imidazoles under solvent-free conditions using molecular iodine as the catalyst is described with excellent product yields.

Catalytic highly enantioselective alkylation of aldehydes with deactivated grignard reagents and synthesis of bioactive intermediate secondary arylpropanols

Because of the high reactivity of Grignard reagents, a direct, highly enantioselective Grignard reaction with aldehydes has rarely been disclosed. In this report, Grignard reagents were introduced with bis[2-(N,N'-dimethylamino)ethyl] ether (BDMAEE) to effectively deactivate their reactivity; thus, a highly enantioselective alkylation of aldehydes with Grignard reagents resulted from catalysis by (S)-BINOL-Ti(O(i)Pr)(2). It is thought that BDMAEE chelates the in situ generated salts MgBr(2) from a Schlenk equilibrium of RMgBr and Mg(O(i)Pr)Br from transmetalation of RMgBr with Ti(O(i)Pr)(4). The Mg salts can actively promote the undesired background reaction to give the racemate. The chelation definitely inhibits the catalytic activity of the Mg salts, suppresses the unwanted background reaction, and enables the highly enantioselective addition catalyzed by (S)-BINOL-Ti(O(i)Pr)(2). Consequently, the Mg salt byproducts were not removed, less Ti(O(i)Pr)(4) than RMgBr was used, and extremely low temperature was avoided in this catalytic asymmetric reaction in comparison with the research disclosed before. Various alkyl Grignard reagents were investigated in the asymmetric addition, and (i)BuMgBr resulted in the highest enantioselectivity, >99%. Furthermore, important intermediate secondary arylpropanols for chiral drug synthesis were effectively synthesized with high enantioselectivity, up to 97%, in one step.

A Solvent-Free Synthesis of 1,2,4,5-Tetrasubstituted Imidazoles Using Molecular Iodine as Catalyst

An efficient method for the synthesis of 1,2,4,5-tetrasubstituted imidazoles by three-component condensation of benzil, benzonitrile derivatives and primary amines under solvent-free conditions using molecular iodine as catalyst is described with high product yields. The significant features of the iodine-catalysed condensation are operational simplicity, inexpensive reagents, high yield of products and use of non-toxic reagents.

Molecular iodine-catalysed amidation reaction of secondary benzylic and allylic alcohols with carboxamides or sulfonamides

A highly efficient method for the C–N bond formation via 2 mol% of molecular iodine-catalysed amidation reaction of benzylic and allylic alcohols with carboxamides or sulfonamides in MeCN is described, giving the corresponding substituted amides and allylic amides in moderate to excellent yields. The significan features of the procedure include mild and metal-free reaction conditions, operational simplicity, inexpensive reagents, short reaction time, and good yields.