The Henry reaction: recent examples

2.1.5. Electrophilic Attack on CdC 3994 2.1.6. NH Insertions in Diazo Compounds 3994 2.1.7. Pd Catalyzed Cyclizations 3994 2.2. Cyclizations by C-C Bond formation 3995 2.2.1. Nucleophilic Displacement of Halides 3995 2.2.2. Cyclizations Involving CdO Group 3995 2.3. Cycloadditions 3996 2.4. Ring Rearrangements 3997 2.4.1. Rearrangements of Four-Membered Rings 3997 2.4.2. Rearrangements of Larger Rings 3998 2.5. Reduction of Azetidin-2-ones 3998 2.6. Miscellaneous Syntheses 3999 2.7. Important Classes of Compounds 4000 2.7.1. Natural Products 4000 2.7.2. Azetidine Carboxylic Acids 4001 2.7.3. Exomethylene Azetidines 4002 2.7.4. Ligands for Metal-Catalyzed Reactions and Chiral Auxiliaries 4003

Novel syntheses of azetidines and azetidinones.

Four-membered ring-containing spirocycles: synthetic strategies and opportunities.

The SAMP-/RAMP-hydrazone methodology in asymmetric synthesis

The well-known properties of the carbonyl group render aldehydes and ketones prominent substrates in both C-C and C-heteroatom bond forming methodologies of organic synthesis. In practical syntheses, nitrogen analogues of aldehydes and ketones such as enamines, imines, or hydrazones, acting as synthetic equivalents of the carbonyl * To whom correspondence should be addressed. E-mail: lazny@uwb.edu.pl. Chem. Rev. 2010, 110, 1386–1434 1386

N,N-dialkylhydrazones in Organic Synthesis. From Simple N,N-dimethylhydrazones to Supported Chiral Auxiliaries

Simple and efficient conversion of N,N-dimethylhydrazones and aldehydes to nitriles.

Formaldehyde SAMP-Hydrazone as a Neutral Chiral Formyl Anion and Cyanide Equivalent: Asymmetric Michael Additions to Nitroalkenes

A versatile methodology for the nucleophilic formylation and cyanation of conjugated enones is reported. The procedure is based on the use of formaldehyde dimethylhydrazone, which, acting as a neutral formyl anion equivalent, adds to preformed trialkylsilyl−enone complexes. Both 4-(silyloxy)-3-enal hydrazones 3 or deprotected 4-oxo aldehyde monohydrazones 4 can be obtained as products depending on quenching conditions. In full analogy, an asymmetric version of the reaction using chiral formaldehyde SAMP-hydrazone as a neutral synthon of the chiral formyl anion has been developed, giving rise to the corresponding adducts 5 and 6 in good yields and with excellent diastereoselectivities (de 85−≥98%). Ozonolysis or HCl-mediated hydrolysis of adducts 4 and 6 readily affords racemic and optically enriched 4-oxo aldehydes 7, respectively. Additionally, high-yielding MMPP-oxidative cleavage of 4-oxo hydrazones 4 and 6 has been performed to obtain 4-oxo nitriles 8 in racemic and optically enriched forms, respectiv...

Formaldehyde Dialkylhydrazones as Neutral Formyl Anion and Cyanide Equivalents: Nucleophilic Addition to Conjugated Enones

A stereocontrolled synthesis of pyranoid and furanoid spironucleosides and spiro- C -glycosides ( d - ribo and d - arabino configurations) of oxazolidines, oxazolines and perhydrooxazines via isothiocyanato sugar derivatives is reported. The intermediate isothiocyanates are prepared from sugar spiroketals by stereoselective opening of the acetal ring with trimethylsilyl N - and C -nucleophiles, and later formation of the isothiocyanato group.

Isothiocyanato derivatives of sugars in the stereoselective synthesis of spironucleosides and spiro-C-glycosides

A new stereocontrolled and high yielding synthesis of biologically active polyhydroxyperhydroazepines is reported starting from easily available glycosylenamines (D-gluco ,D -manno, and D-galacto configurations), which are transformed into 1,6-azaanhydropyranose derivatives. O -a ndN-Deprotection of the latter, followed by reduction with sodium cyanoborohydride, gives the target chiral iminocyclitols. The method is based on the capacity of the dialkoxycarbonylvinyl group to stabilize an amide ion, and the only limitation is the necessity for the starting glycosylenamine to have -D-configuration. The inhibitory activity of several intermediate iminocyclitols and aldopyranosylenamines on different - and -glycosidases is also reported. © 2002 Published by Elsevier Science Ltd.

http://busca-tox.com/05pub/An%20easy%20route%20to%20seven-membered%20iminocyclitols%20f%20aldohexopyranosyl%20enamines,%20Tetrah%20Asym%202002.pdf

Consolación Gasch

Papers

Simple and efficient conversion of N,N-dimethylhydrazones and aldehydes to nitriles.

Formaldehyde SAMP-Hydrazone as a Neutral Chiral Formyl Anion and Cyanide Equivalent: Asymmetric Michael Additions to Nitroalkenes

Formaldehyde Dialkylhydrazones as Neutral Formyl Anion and Cyanide Equivalents: Nucleophilic Addition to Conjugated Enones

Isothiocyanato derivatives of sugars in the stereoselective synthesis of spironucleosides and spiro-C-glycosides

An easy route to seven-membered iminocyclitols from aldohexopyranosyl enamines