Rosario Fernández

C2-Symmetric Bis-Hydrazones as Ligands in the Asymmetric Suzuki-Miyaura Cross-Coupling

Glyoxal bis-hydrazone derived from (S,S)-1-amino-2,5-diphenylpyrrolidine behaves as an excellent ligand for phosphine-free, asymmetric Suzuki-Miyaura cross couplings, thereby affording a variety of enantiomerically enriched biaryls with different substitution patterns. The high catalytic activity of the [PdCl2(bis-hydrazone)] complex allows reactions to be performed at room temperature, affording products with excellent enantioselectivities in all cases.

Axially chiral triazoloisoquinolin-3-ylidene ligands in gold(I)-catalyzed asymmetric intermolecular (4 + 2) cycloadditions of allenamides and dienes.

The first highly enantioselective intermolecular (4 + 2) cycloaddition between allenes and dienes is reported. The reaction provides good yields of optically active cyclohexenes featuring diverse substitution patterns and up to three stereocenters. Key to the success of the process is the use of newly designed axially chiral N-heterocyclic carbene-gold catalysts.

Use of Hemilabile N,N Ligands in Nitrogen‐Directed Iridium‐Catalyzed Borylations of Arenes

We thank the Spanish “Ministerio de Ciencia e Innovacion” (grants CTQ2010-15297 and CTQ2010-14974, and fellowship to B.E.), the European FEDER funds and the Junta de Andalucia (grants 2008/FQM-3833 and 2009/FQM-4537) for financial support. A.R. thanks the EU for a Marie Curie Reintegration Grant (FP7-PEOPLE-2009-RG-256461) and R.L.-R. thanks CSIC for a JAE predoctoral fellowship.

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

Aldehyde N,N-dimethylhydrazones undergo facile oxidative cleavage to nitriles on reaction with magnesium monoperoxyphtalate hexahydrate (MMPP)

Phosphino hydrazones as suitable ligands in the asymmetric Suzuki-Miyaura cross-coupling

Phosphino hydrazones derived from C(2)-symmetric hydrazines exhibit excellent catalytic activity and provide good enantioselectivities in the asymmetric Suzuki-Miyaura cross-coupling to axially chiral biaryls, in particular for the most challenging reactions of monocyclic, functionalized aryl bromides and triflates. X-ray analysis of preformed [Pd(P/N)Cl(2)] precatalysts [(P/N) = phosphino hydrazone] revealed a strong n-π conjugation in the hydrazone moiety, identified by a high planarity degree at the pyrrolidine N(sp(3)) atom, that makes rotations around N-N bonds inconsequential. The complexes are also characterized by an envelope-like conformation with the Pd atom placed at the opposite side to the 2-phenyl group on the nearest stereogenic center of the pyrrolidine group. The isolation and structural analysis of oxidative addition intermediates indicate that the configurational stability of Pd-C(Ar) bonds is dependent on the substitution pattern in the aryl bromide.

Asymmetric formal carbonyl-ene reactions of formaldehyde tert -butyl hydrazone with α-keto esters: Dual activation by bis-urea catalysts

The dual activation of α-keto esters and formaldehyde tert-butyl hydrazone by BINAM-derived bis-ureas is the key to achieve high reactivity and excellent enantioselectivities in nucleophilic addition (formal carbonyl-ene reaction) to functionalized tertiary carbinols. Ensuing high-yielding diazene-to-aldehyde tranformations and subsequent derivatizations provides a direct entry to a variety of densely functionalized products.

Isoquinolin-1-ylidenes as electronically tuneable ligands

The novel isoquinolin-1-ylidene ligands, introduced into Rh(I) complexes by exploiting the carbene-like reactivity of adducts , exhibit ligand properties similar to those of classic NHCs, and their electronic properties can be tuned by the introduction of electron-withdrawing or donating groups in the benzene ring.

Synthesis of Enantiopureα-Alkoxy-α-Trifluoromethyl Aldehydes and Carboxylic Acids from Trifluoromethyl Ketones

Formaldehyde dialkylhydrazones behave as neutral d1 synthons in their uncatalyzed reaction with trifluoromethyl ketones (see reaction). Both racemic and optically pure 1,2-adducts were obtained in good yields. Efficient deprotection of the hydrazone moiety afforded interesting fluorinated quaternary compounds such as 1 and 2.

Michael addition of formaldehyde dimethylhydrazone to nitroolefins. A new formyl anion equivalent

Abstract Formaldehyde dimethylhydrazone readily adds to simple nitro-olefins in the absence of base giving β-nitrodimethylhydrazones in very high yields. The corresponding β-nitroaldehydes can be obtained by ozonolysis.

Highly efficient nitroaldol reaction promoted by trialkylsilyl chlorides

β-Nitroalcohols can be readily obtained in high yields by the one-pot reaction of aldehydes with nitrecompounds in the presence of Et3N, Bu4NF·3H2O and tBuMe2SiCl. Model experiments indicated that trialkylsilyl nitronic esters are not reaction intermediates.