M. Montserrat Martínez

Microwave enhanced synthesis of 4-aminoquinazolines

Abstract Cyanoaromatic compounds react with anthranilonitrile in a domestic microwave oven affording good yields of the corresponding 4-aminoquinazolines in a very short irradiation time.

Synthesis of β-phenylethylamines from styrene derivatives

Abstract β-Phenylethylamines are prepared from the styrene derivatives: 4,4-dimethyl-2-(2-vinylphenyl)-2-oxazoline, 2-(3-methoxy-2-vinylphenyl)-4,4-dimethyl-2-oxazoline, 2-vinylbenzoic acid, styrene, (3-methylstyrene, and α-methylstyrene.

Total Synthesis of (+)-Neomarinone

The first total synthesis of (+)-neomarinone has been achieved by following a concise and convergent route using methyl (R)-lactate and (R)-3-methylcyclohexanone as chiral building blocks. Key steps of the synthesis are the stereocontrolled formation of the two quaternary stereocenters by diastereoselective 1,4-conjugate addition and enolate alkylation reactions, and the construction of the furanonaphthoquinone skeleton by regioselective Diels-Alder reaction between a 1,3-bis(trimethylsilyloxy)-1,3-diene and a bromoquinone. The synthesis proves the relative and absolute stereochemistry of natural neomarinone.

A Versatile Enantioselective Synthesis of Barrenazines

A versatile enantioselective total synthesis of barrenazines A and B has been accomplished from 1,4-butanediol. The key steps of the synthesis are a sequential allylboration/ring-closing metathesis for the construction of the tetrahydropyridine ring and the preparation of a functionalized 4-azidopiperidin-5-one through a stereoselective epoxidation and regioselective ring-opening reaction. The C(2)-symmetrical pyrazine skeleton of barrenazines was prepared by dimerization of the azidopiperidinone, and the carbon side chain was completed by copper-catalyzed reactions using Grignard reagents.

Microwave enhanced synthesis of acridines. A new aspect in the Bernthsen reaction

The Bernthsen reaction is studied using microwaves as the heat source. This leads to acridines with aromatic and aliphatic substituents in position 9, shortening reaction times and increasing yields, with a reduction in Lewis acid catalyst (ZnCl2), allowing a more environmentally friendly reaction.

Triorganoindium Reagents in Selective Palladium-Catalyzed Cross-Coupling with Iodoimidazoles: Synthesis of Neurodazine

Triorganoindium reagents (R3In, R = aryl, heteroaryl, alkynyl) react selectively under palladium catalysis with N-benzyl-2,4,5-triiodoimidazole to afford the C-2 monocoupling products. The reaction proceeds efficiently for a variety of aryl- and heteroarylindium reagents with the transfer of all three organic groups attached to the metal. The coupling products can be used in a subsequent two-fold cross-coupling to give trisubstituted imidazoles in good yields. This approach was employed to synthesize neurodazine and analogues in good yields.

Direct Synthesis of Imides from Dicarboxylic Acids using Microwaves

1,4- and 1,5-dicarboxylic acids, when treated with amines in a domestic microwave oven, afford good yields of the corresponding imides.

1,6-conjugate addition to o-vinylphenyloxazolines. Syntheses of chuangxinol and 3-n-butylphthalide

Abstract Phtalhides are prepared from o-vinylphenyloxazolines in one pot reaction by 1,6-conjugate addition of alkyllithium and trapping of the benzylic anion with MoOPH, followed by hydrolysis with aqueous oxalic acid. This method was applied to the syntheses of two natural products: chuangxinol and 3-n-butylphthalide.

A Versatile Synthesis of Fumaquinone

Fumaquinone, a novel prenylated naphthoquinone antibiotic, was synthetized from ethyl acetoacetate in three steps (58% overall yield). The key step of the synthesis is the construction of the naphthoquinone skeleton by a regioselective Diels-Alder reaction between a 2-alkyl 1,3-bis(trimethylsilyloxy)-1,3-diene derivative and a bromoquinone. This short and versatile approach confirms the structure of fumaquinone and allows the synthesis of derivatives at the C-6 position.

Sequential In-catalyzed intramolecular hydroarylation and Pd-catalyzed cross-coupling reactions using bromopropargyl aryl ethers and amines

A sequential one-pot indium-catalyzed intramolecular hydroarylation (IMHA) of bromopropargyl aryl ethers and amines, and palladium-catalyzed cross-coupling reaction using triorganoindium reagents (R3In) has been developed. In this transformation, the IMHA of 3-bromo-2-propynyl aryl ethers under indium(III) catalysis, proceeds regioselectively through a 6-endo dig pathway to afford 4-bromo-2H-chromenes. Subsequent palladium-catalyzed cross-coupling with R3In gives 4-substituted-2H-chromenes in one-pot. This sequential transformation was extended to 3-bromo-2-propynyl-N-tosylanilines to afford 4-substituted-1,2-dihydroquinolines. The dual-catalyzed procedure takes place efficiently with a variety of propargyl aryl ethers and amines and R3In (R = aryl, heteroaryl, alkyl or alkynyl), showing the efficiency of these organometallics and proving the compatibility of indium and palladium in catalysis.