Search results for "BIF"

Organocatalytic enantioselective aza-Friedel–Crafts reaction of 2-naphthols with benzoxathiazine 2,2-dioxides

2015

An organocatalytic enantioselective aza-Friedel–Crafts addition of 2-naphthols to benzoxathiazine 2,2-dioxides is described using a quinine-derived bifunctional catalyst. The method allows the use of a wide range of aromatic compounds as nucleophiles, including 1-naphthol and sesamol, and benzoxathiazines 2,2-dioxides, expanding the existing state of the art enantioselective synthesis of aminomethylnaphthol derivatives.

ChemInform Abstract: Organocatalytic Enantioselective Aza-Friedel-Crafts Reaction of 2-Naphthols with Benzoxathiazine 2,2-Dioxides.

2015

An organocatalytic enantioselective aza-Friedel–Crafts addition of 2-naphthols to benzoxathiazine 2,2-dioxides is described using a quinine-derived bifunctional catalyst. The method allows the use of a wide range of aromatic compounds as nucleophiles, including 1-naphthol and sesamol, and benzoxathiazines 2,2-dioxides, expanding the existing state of the art enantioselective synthesis of aminomethylnaphthol derivatives.

ChemInform Abstract: Cooperative Assistance in Bifunctional Organocatalysis: Enantioselective Mannich Reactions with Aliphatic and Aromatic Imines.

2013

both of which contain a thiourea moiety (Scheme 1).The catalysts are capable of deprotonating suitable nucleo-philes, such as activated carbonyl compounds. This proton-transfer reaction generates an ion pair, which is composed ofthe protonated catalyst and the anionic nucleophile interact-ing through hydrogen bonds. At least one of the NH moietiesin the protonated catalyst is involved in activating theelectrophilic reaction partner.

ChemInform Abstract: Heterocycles from α-Aminonitriles

2014

Owing to their various modes of reactivity, α-aminonitriles represent versatile building blocks for the construction of a wide range of nitrogen heterocycles. The present Concept article focuses on synthetic methodologies using their bifunctional nature which is the basis of their reactivity as α-amino carbanions and as iminium ions. Reactions exclusively taking place on either the amine or on the nitrile moiety will not be considered.

1976

ChemInform Abstract: Fluorous TBAF: A Convenient and Selective Reagent for Fluoride-Mediated Deprotections.

2010

A fluorous analogue of TBAF has been developed for its use in the clean removal of silicon-derived protecting groups. Purification of the crude mixtures by fluorous solid-phase extractions allowed alcohols, amines, and carboxylic acids to be obtained in high purity, with no need of chromatographic separations. The moderate reactivity of fluorous TBAF was exploited in selective deprotections of several bifunctional molecules.

Synthese von methyl- und methylenosubstituierten p-Oligophenylenen durch cokondensierende ULLMANN-Reaktion. 12. Mitt.

1963

Es wird ein Syntheseverfahren fur p-Oligophenylene beschrieben, das eine Variante der ULLMANNschen Biarylverknupfungsreaktion darstellt. Dabei wird eine bifunktionelle Jodverbindung mit einem groseren Uberschus an einer monofunktionellen Komponente umgesetzt. Dieses als cokondensierende ULLMANN-Reaktion bezeichnete Syntheseprinzip, das Ausbeuten von 40–50% d. Th. ergibt, wird eingehend erlautert und die Leistungsfahigkeit an zahlreichen Beispielen belegt. Neben einer Reihe von methylsubstituierten p-Oligophenylenen, welche Derivate vom p-Terphenyl bis zum p-Septiphenyl einschliest, werden auch Oligophenylene mit endstandigem oder mittelstandigem Fluorenrest als Strukturelement hergestellt. …

Organocatalytic Domino Oxa-Michael/1,6-Addition Reactions: Asymmetric Synthesis of Chromans Bearing Oxindole Scaffolds.

2016

An asymmetric organocatalytic domino oxa-Michael/1,6-addition reaction of ortho-hydroxyphenyl-substituted para-quinone methides and isatin-derived enoates has been developed. In the presence of 5 mol % of a bifunctional thiourea organocatalyst, this scalable domino reaction affords 4-phenyl-substituted chromans bearing spiro-connected oxindole scaffolds and three adjacent stereogenic centers in good to excellent yields (up to 98 %) and with very high stereoselectivities (up to >20:1 d.r., >99 % ee).

A girl with inverted triplication of chromosome 3q25.3 → q29 and multiple congenital anomalies consistent with 3q duplication syndrome

2005

We report a newborn girl with intrachromosomal triplication of 3q25.3 --> q29 (mosaicism) who died at the age of 3.5 weeks due to her malformations. She demonstrated disproportionate short stature with short limbs, a prominent and hairy forehead, thick eyebrows, synophrys, small upturned nose, full cheeks, micrognathia, and low set malformed and posteriorly rotated ears, short and webbed neck, hydrocephalus, Dandy-Walker malformation, spina bifida, complex heart defect (ventricular and atrial septal defect, malrotation, and interrupted aortic arch), omphalocele, polycystic kidneys, postaxial polydactyly of left hand, and generalized hirsutism; all signs have been associated with the dup(3q)…

2015

Study que Stion What are the long term trends in the total (live births, fetal deaths, and terminations of pregnancy for fetal anomaly) and live birth prevalence of neural tube defects (NTD) in Europe, where many countries have issued recommendations for folic acid supplementation but a policy for mandatory folic acid fortification of food does not exist? Method S This was a population based, observational study using data on 11 353 cases of NTD not associated with chromosomal anomalies, including 4162 cases of anencephaly and 5776 cases of spina bifida from 28 EUROCAT (European Surveillance of Congenital Anomalies) registries covering approximately 12.5 million births in 19 countries betwe…