UV photodissociation of 2,3-, 2,5-, and 2,6-dimethylpyrazine.

ABSTRACT: A mesoinic pyridylideneamide ligand (PYA) was synthetized and fully characterized and coordinated to an iridium(III) center. This ligand represents the first example of a mesoionic N-donor ligand. Structural and spectroscopic analysis revealed unique properties which were exploited in chemically driven water oxidation catalysis.

The bis(oxazoline)s 4a-4c were obtained basically according to the reported method[4].

N2 - The enantioselective [2,3]-Wittig rearrangement of benzyl prenyl ether has been studied. Treatment of this ether with butyl lithium bearing diamines or bis(oxazoline)s as external chiral ligands (ECL) gave the expected alcohol in up to 66% ee, the highest reported for this transformation. The optimum ECL is based on the bis(oxazoline) system and the C5 substituent on the bis(oxazoline) is crucial to determining both the degree and sense of asymmetric induction. (C) 2004 Elsevier Ltd. All rights reserved.


S., Ethyl 2-(4-phenyl-1-1,2,3-triazol-1-yl)acetate.

"Click Labeling" with 2-[18F]Fluoroethylazide for Positron Emission Tomography.

AB - Indane-derived bis(oxazolines) were synthesized in two steps and 93% overall yield starting from commercially available substrates. This ligand is as effective as tert-butyl bis(oxazoline) in hetero Diels-Alder reaction both in solution and on polymer support.


Chiral Bis(oxazoline) Ligands,Chiral Bis(oxazoline) Ligands

An oven-dried, 250-mL, two-necked, round-bottomed flask equipped with a condenser fitted with an argon inlet and a magnetic stirbar was purged with argon for 10 min. Anhydrous THF (200 mL) (Note 1) was added into the flask by syringe through the open neck under a positive pressure of argon. Next, lithium aluminum hydride (4.56 g, 120 mmol, 1.50 equiv) (Note 2) was added over 5 min through the open neck under a positive pressure of argon. The solution was stirred at rt for 5 min, and then -homophenylalanine ethyl ester hydrochloride (19.5 g, 80.0 mmol, 1.00 equiv) (Note 6) was added in portions (500 mg per portion) over 10 min through the open neck under a positive pressure of argon, during which time the solution gently refluxed. Upon the completion of the addition, the open neck was capped, and the heterogeneous gray reaction mixture was heated at reflux in an oil bath for 24 h. Next, the mixture was allowed to cool to rt, THF (100 mL) was added, and the solution was cooled to 0 °C in an ice bath. Water (10 mL) was added dropwise over 10 min (Note 4), and then a solution of NaOH (2.5 M, 20 mL) was added in one portion. The resulting mixture was heated at reflux for 20 min until the color of the precipitate changed from gray to white. The warm solution was filtered through a Büchner funnel that contained a bed of celite (1.0 cm height), and the precipitate was washed with warm THF (100 mL). The filtrate was concentrated under reduced pressure (20 torr) to remove the THF and most of the water. The residue was dried azeotropically with toluene (two 50-mL portions) by rotary evaporation (20 torr) and then under high vacuum (0.5 torr) for 2 h, which yielded the desired β-amino alcohol 2 as a white solid (12.5-13.0 g, 94-98% yield) (Note 7) that was used in the next step without further purification.

Bis oxazoline ligand synthesis essay - LayoutPress

Starting from (,)-1,1′-bis(4-isopropyloxazolin-2-yl)ferrocene, all possible 2-trimethylsilyl- and 2,2′-di(trimethylsilyl)-substituted diastereoisomers, potential bisoxazoline ligands for use in asymmetric catalysis, were synthesised by selective lithiation followed by addition of trimethylsilyl chloride. Access to the (,, p, p)-diastereoisomer was achieved following diastereoselective introduction of two deuterium-blocking groups and utilisation of the high H/ D value for lithiation, methodology that was also applied to the synthesis of a related 2,2′-di(diphenylmethanol)bisoxazoline ligand.

Bis oxazoline ligand synthesis essay - Littere

Starting from (,)-1,1′-bis(4-isopropyloxazolin-2-yl)ferrocene, all possible 2-trimethylsilyl- and 2,2′-di(trimethylsilyl)-substituted diastereoisomers, potential bisoxazoline ligands for use in asymmetric catalysis, were synthesised by selective lithiation followed by addition of trimethylsilyl chloride. Access to the (,, p, p)-diastereoisomer was achieved following diastereoselective introduction of two deuterium-blocking groups and utilisation of the high H/ D value for lithiation, methodology that was also applied to the synthesis of a related 2,2′-di(diphenylmethanol)bisoxazoline ligand.