Imines olefination

A range of secondary A-alkylanilines undergo oxidative olefination with 2-alkyl-quinoline, 4-methylquinoline, 1-methylisoquinoline, 2-methylquinoxaline, 2-methyl-quinazoline, 2-methylbenzo[fiG-thiazole, acetophenone, and malononitrile in DMF to form structurally diverse polysubstituted alkenes in moderate to excellent yields with excellent E Z >99 1 selectivity with the use of 2,3-dichloro-5,6-dicyano-l,4-benzoquinone as the oxidant. Mechanistically, the oxidative olefination reaction proceeds through amine oxidation followed by imine olefination." ii... 

Work with Rh catalyst precursors in the Ellman group has resulted in the development of addition reactions of C—H bonds to unsaturated bonds in imines, olefins, isocyanates, or aldehydes through Rh-aryl intermediates 35. The resulting protocols form new C—C bonds in the process and many interesting heterocyclic structures such as 37, 38, and 39 can be synthesized. ... 

Alkanolamines [ALKANOLAMINES - ALKANOLAMINES FROM OLEFIN OXIDES AND AL ONIA] (Vol 2) -polymerization of [IMINES, CYCLIC] (Vol 14)... 

A simple preparative route to the previously unknown lH-3-pyrazolines via azomethine imines was developed. Olefins of the type R cH=CHR react with hexafiuoroacetone azine to give azomethine mines, which undergo a sequence of prototropic shifts to form 17/-3-pyrazolines [196, 202], On heating, the latter are transformed into 3-trifluoromethylpyrazoles [196, 206] and, on treatment with bases, into 1,2,5,6-tetrahydropynmidines [206] (equation 45)... 

The Corey-Chaykovsky reaction entails the reaction of a sulfur ylide, either dimethylsulfoxonium methylide (1, Corey s ylide, sometimes known as DMSY) or dimethylsulfonium methylide (2), with electrophile 3 such as carbonyl, olefin, imine, or thiocarbonyl, to offer 4 as the corresponding epoxide, cyclopropane, aziridine, or thiirane. ... 

Substituted TMMs also participate smoothly in imine cycloaddition to generate more structurally elaborate pyrrolidines. The regioselectivity of these reactions is similar to that of olefin addition, although subsequent isomerization of the initial adduct is often observed. For example, the cyano system produced the thermody-... 

Diastereoselective preparation of a-alkyl-a-amino acids is also possible using chiral Schiff base nickel(II) complexes of a-amino acids as Michael donors. The synthetic route to glutamic acid derivatives consists of the addition of the nickel(II) complex of the imine derived from (.S )-,V-[2-(phenylcarbonyl)phenyl]-l-benzyl-2-pyrrolidinecarboxamide and glycine to various activated olefins, i.e., 2-propenal, 3-phenyl-2-propenal and a,(f-unsaturated esters93- A... 

One of the earliest reported thermal reactions of Fischer carbene complexes was the reaction with olefins to give cyclopropanes [127]. More recently it has been shown that photolysis accelerates inter molecular cydopropanation of electron-poor alkenes [128]. Photolysis of Group 6 imine carbenes with alkenes... 

Several studies characterizing the reactions of alkenyl radicals with quinone dumines and quino-neimines were published in the late 1970s. Quinone dumines react with allylic radicals yielding both the reduced PPD and the alkylated product. In these experiments 2-methyl-2-pentene served as a model olefin (model for NR). Samples of the olefin and quinoneimines or quinone diimine were heated to 140°C. Isolation and analysis of products demonstrated that 40%-70% of the imine or diimine was reduced to the corresponding PPD, while 20%-50% was isolated as the alkylated product. This alkylation reaction (via an allylic radical) represents the pathway to the formation of rubber-bound antidegradant. ... 

Dipolar cycloaddition of azides with olefins provides a convenient access to triazolines, cyclic imines, and aziridines and hence is a valuable technique in heterocyclic synthesis. For instance, tricyclic -lactams 273 - 276 have been synthesized using the intramolecular azide-olefin cycloaddition (lAOC) methodology (Scheme 30) [71]. 

Scheme 8.12 Hydrogenations of olefins with BINOL-derived A -phosphino sulfox-imine ligands.

Scheme 8.14 Hydrogenation of olefin with P/N-sulfinyl imine ligands.

This chapter discusses the development of scaleable and robust manufacturing processes for rhodium and rathenium containing precatalysts that are used for the asymmetric hydrogenation of a diverse range of olefins, ketones and imines. The application of these precatalysts to the preparation of a variety of pharmacentical intermediates, many of which have been operated on commercial scale, is also discussed. 

It has also been shown that dimethylsilyl enolates can be activated by diisopropylamine and water and exhibit a high reactivity toward iV-tosyl imines to give Mannich-type reaction products in the absence of a Fewis acid or a Bronsted acid.51 For example, the reaction of [(1-cyclohexen-l-yl)oxy]dimethylsilane with 4-methyl-A -(phenylmethylene)benzene sulfonamide gave re/-4-methyl-N- (f )-[(15)-(2-oxocyclohexyl)phenyl-methyl] benzenesulfonamide (anti-isomer) in 91% yield stereoselectively (99 1 anti syn) (Eq. 11.30). On the other hand, Fi and co-workers reported a ruthenium-catalyzed tandem olefin migration/aldol and Mannich-type reactions by reacting allyl alcohol and imine in protic solvents.52... 

The scheme required to prepare the potent tri-fluoro corticoid cormethasone acetate (292) illustrates the synthetic complexities involved in some of this work. Sequential acetylation of the pregnenolone derivative 278 with first acetic anhydride in pyridine and then acetic anhydride in the presence of tosic acid affords diacetate 279. Reaction of that intermediate with nitrosyl fluoride results initially in addition of the reagent to the 5,6-olefin moiety to afford the fluoro oxime reaction with a second mole of reagent at nitrogen gives the nitroimine derivative 280 passage over alumina serves to hydrolyze the imine function to the corresponding 6-ketone (281). 

It is of interest that antibacterial activity can be retained even when the imine carbon-nitrogen bond is replaced by a carbon to carbon double bond. Base-catalyzed condensation of 5-nitrofurfuraldehyde (24) with 2,6-dimethylpyridine (38) affords olefin 39. Treatment of this compound with hydrogen peroxide gives the corresponding N-oxide (40). Heating of... 

Optically active oxaziridines are useful reagents for the enantioselective oxidation of olefins 37 39). The following three preparative methods to make this reagent available have been reported enantioselective oxidation of an imine by (-)-peroxycam-phoric acid 37,38), photocyclization of a nitrone which has a chiral substituent39), and photocyclization of a nitrone in an optically active solvent 39). However, an... 

In the Jacobsen catalyst, the presence of the four tert-butyl groups disfavors all side-on olefin approaches with the exception of the approach from the di-imine bridge (3 in Fig. 7.5).190,199... 

The analytical data obtained, particularly by the PUMA mass spectrometer on board Vega 1 during the flyby, indicate the presence of a large number of linear and cyclic carbon compounds, such as olefins, alkynes, imines, nitriles, aldehydes and carboxylic acids, but also heterocyclic compounds (pyridines, pyrroles, purines and pyrimidines) and some benzene derivatives no amino acids, alcohols or saturated hydrocarbons are, however, present (Kissel and Krueger, 1987 Krueger and Kissel, 1987). 

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