Francisco Foubelo

Diastereoselective allylation of carbonyl compounds and imines: application to the synthesis of natural products.

We thank the Spanish Ministerio de Ciencia e Innovacion (Grant Nos. CTQ2007-65218 and Consolider Ingenio 2010-CSD-2007-00006 and CTQ2011-24165), the Generalitat Valenciana (Grant No. PROMETEO/2009/039 and FEDER), and the University of Alicante for generous and continuous financial support.

The role of 1,3-dithianes in natural product synthesis

0040–4020/

Stereoselective α-Aminoallylation of Aldehydes with Chiral tert-Butanesulfinamides and Allyl Bromides†

- see front matter q 2003 Elsevier Ltd. All rights reserved.doi:10.1016/S0040-4020(03)00955-4Tetrahedron 59 (2003) 6147–6212* Corresponding author. Tel.: þ34-965-909672; fax: 34-965-903549; e-mail: foubelo@ua.esKeywords: carbanions; organolithium compounds; dithioacetal moiety.Abbreviations: A-15E, Amberlyst 15E; 9-BBN, 9-borabicyclo[3.3.1]nonane; Bn, benzyl; Boc, t-butoxycarbonyl; BOM, benzyloxymethyl; Bz, benzoyl; 12-C-4, 12-crown-4; CSA, 10-camphorsulfonic acid; CIP, contact ion pairs; DEAD, diethyl azo dicarboxylate; DEIPS, diethylisopropylsilyl; DHP, dihydropyran;DIBALH, diisobutylaluminium hydride; DMB, 3,4-dimethoxyphenylmethyl; DMF, dimethylformamide; DMPU, N,N

1,2-Di(lithiomethyl)benzene from phthalan: Sequential introduction of two different electrophiles☆

The combination of an aldehyde, an allylic bromide, and tert-butanesulfinamide in the presence of indium metal and titanium tetraethoxide allows straightforward access to homoallylamine derivatives in high yields and stereoselectivities. Moreover, the synthetic utility of the enantioenriched homoallylamine derived from n-decanal was illustrated in a concise synthesis of (+)-isosolenopsin. In this context, similar homoallylamines has been recently used by other groups in the synthesis of naturally occurring alkaloids.

Aromatic iodination with the I2-HgX2 combination

Abstract The reaction of phthalan ( 1 ) with an excess of lithium powder and a catalytic amount of DTBB (2.5 mol %) in THF at 20°C followed by treatment with electrophiles (D 2 O, CO 2 and carbonyl compounds) at −78°C leads, after hydrolysis, to the corresponding functionalised benzylic alcohols 3a-g . When the lithiation reaction is continued, after the reaction with the first electrophile, and a second electrophile (H 2 O, D 2 O and carbonyl compounds) is added, the corresponding disubstituted compounds 6a-q are prepared. Diols 3c-g and 6h,i,l,n and hydroxyacids 6a,c,f,k are easily dehydrated to the corresponding cyclic ethers ( 7c-f, 8h,i,l,n ) or lactones ( 9a,c,f,k ), respectively. Finally, alcohols 6b,d,e give, after acid treatment, the Friedel-Crafts type benzocyclopentenes 10b,d,e .

Naphthalene-catalysed reductive opening of aziridines with lithium: A direct preparation of n-lithio-2-lithioalkylamines

Abstract The reaction of different aromatic compounds 1a – 1t with iodine and a mercury(II)-salt 2 [mercury(II) chloride, nitrate or triflate] (1:1:1 molar ratio) in dichloromethane at room temperature leads to the corresponding iodoarene 3 , the obtained regiochemistry being the expected. Concerning the mercury(II) salt, the observed reactivity decreased in the series triflate&>nitrate&>chloride according to their ionic character. An activation of the iodine molecule by the mercury(II) salt followed by a S E reaction with the aromatic compound is postulated as the possible mechanism.

Efficiency in chemistry: from hydrogen autotransfer to multicomponent catalysis

Abstract The reductive opening of N -phenylaziridine ( 1 ) with an excess of lithium presence of a catalytic amount (5 molar %) of naphthalene at −78°C leads to the corresponding N -lithio-2-lithioethylamine ( 2 ), which by reaction with different electrophiles (water, deuterium oxide, dimethyl disulphide, pivalaldehyde or cyclohexanone) affords the expected product ( 3 ). The same process applied to N -cyclohexylaziridine fails. The reactions also works with the chiral aziridine 4 yielding the chiral deuteriated amine 5 , through the corresponding chiral dianionic intermediate.

Arene 1,4-Diradical Formation from o-Dialkynylarenes

A hydrogen autotransfer reaction has been applied to the α-alkylation of ketones, with primary alcohols as the electrophilic component, either under homogeneous (using a Ru complex as catalyst) or under heterogeneous (using Ni nanoparticles) conditions. This process is both very efficient (concerning atom economy) and ecologically friendly (water as the only by-product generated). On the other hand, three multicomponent reactions, namely, the Strecker reaction (without any catalyst), the aza-Sakurai process (catalyzed by ferrite), and the addition of in situ generated Zn enolates to chiral sulfinylimines (catalyzed by Cu), have proven to be very efficient in the generation of a diversity of polyfunctionalized molecules.

Stereoselective Synthesis of Azetidines and Pyrrolidines from N-tert-Butylsulfonyl(2-aminoalkyl)oxiranes†

Abstract A series of five arene and quinone derivatives with dialkynyl substituents in the ortho positions and fixed in a 10-membered ring were prepared and tested with respect to thermal rearrangement to the corresponding arene 1,4 diradicals.

Lithium 2-(2-lithiomethylphenyl)ethanolate from isochroman: Easy preparation of substituted benzoxepines and functionalised arenes

Base-induced cyclization of enantiopure (2-aminoalkyl)oxiranes allowed the stereospecific formation of pyrrolidin-3-ols and/or 2-(hydroxymethyl)azetidines, depending on the reaction conditions. The oxidation of 2-(hydroxymethyl)azetidines led to azetidine-2-carboxylic acids in high yields.