4.4- Dimethyl-2-oxazoline

Initial polymerization studies were conducted with 2,2 -tetramethylenebls(4,4-dimethyl-2-oxazolin-5-one) 4 and... 

A. 2-(2,3-Dimethoxyphenyl)-4,4-dimethyl-2-oxazoline. To a 100-mL. round-bottomed flask, fitted with a magnetic stirring bar and a reflux condenser and placed in an ice-water bath, is added 24.5 g (0.206 mol) of thionyl chloride (Note 1). To this is added 12.2 g (0.067 mol) of 2,3-dimethoxybenzoic acid (Note 2). The resulting mixture is stirred at 0°C for 1 hr and then at room temperature for 24 hr. Excess thionyl chloride is removed by rotary evaporation (HOOD ) and the residue is distilled using a Kugelrohr apparatus at 105°C (0.05 mm) to give 12.7-13.1 g of 2,3-dimethoxybenzoyl chloride, which crystallizes on cooling (Note 3). 

Dimethoxyphenyl)-4,4-dimethyl-2-oxazoline Oxazole, 2-(2,3-dimethoxyphenyl)-4,5-dihydro-4,4-dimethyl- (9) (57598-32-0)... 

Like most aryl halides, furyl halides and furyl triflates have been coupled with a variety of organostannanes including alkenyl, aryl, and heteroaryl stannanes in the presence of catalytic palladium. Carbamoylstannane 66 was prepared by treating lithiated piperidine with carbon monoxide and tributyltin chloride sequentially. The Stille reaction of 66 and 3-bromofuran then gave rise to amide 67 [61]. In another example, lithiation of 4,4-dimethyl-2-oxazoline followed by quenching with MesSnCl resulted in 2-(tributylstannyl)-4,4-dimethyl-2-oxazoline (68) in 70-80% yield [62], Subsequent Stille reaction of 68 with 3-bromofuran afforded 2-(3 -furyl)-4,4-dimethyl-2-oxazoline (69). 

N,4,4-Trimethyl-2-oxazolinium iodide is prepared by adding 49.5 g. (0.5 mole) of 4,4-dimethyl-2-oxazoline to an excess of cold methyl iodide (182 g., 80 ml., 1.28 moles) in a 500-ml. flask and stirring at room temperature under argon for 20 hours. The light brown solid is filtered with the aid of suction and then dissolved in 350 ml. of dry acetonitrile. The methiodide salt is precipitated by the addition of 750 ml. of dry ether to this acetonitrile solution. The purified salt is again filtered with the aid of suction, and the white solid is washed with 250 ml. of dry ether and finally dried under vacuum. This gives 96 g. (80%) of the methiodide, m.p. 215° (dec.). 

ALDEHYDES FROM 4,4-DIMETHYL-2-. OXAZOLINE AND GRIGNARD REA-j GENTS O-ANISALDEHYDE, 54,... 

Dimethyl-2-oxazoline is commercially available from Columbia Organic Chemicals, 912 Drake Street, Columbia, South Carolina, or may be prepared as follows. In a 250-ml., three-necked flask is placed 89.14 g. (1.0 mole) of 2-amino-2-methyl-l-propanol, and the flask is cooled in an ice bath. The amine is carefully neutralized with 52.3 g. (1.0 mole) of 90.6% formic acid over a 1-hour period. A magnetic stirring bar is added, the flask is fitted with a short path distillation head, and the reaction mixture is placed in a silicon oil bath which is rapidly heated to 220-250°. The azeotropic mixture of water and oxazoline distills over a period of 2-4 hours and is collected in an ioe-cooled flask containing ether. The aqueous layer is separated, saturated with sodium chloride, and extracted with three 50-ml. portions of ether. The combined ethereal extracts are dried over potassium carbonate, filtered to remove the drying agent, and the ether is removed at 35-40° at atmospheric pressure. The 4,4-dimethyl-2-oxazoline is collected as the temperature rises above 85°. The yield is 56.7-62.7 g. (57—63%) of a colorless mobile liquid, b.p. 99-100° (758 mm. Hg). 

Carbonyl alkylation and condensation reactions are always of great value in synthesis, and the formation of o-ANIS ALDEHYDE via 4,4-dimethyl-2-oxazoline, 2,2-DIMETHYL-3-PHENYLPROPION-ALDEHYDE via alkylation of the magnesio-enamine salt and threo-4-HYDROXY-3-PHENYL-2-HEPTANONE via a directed aldol... 

A variety of heterocyclic systems containing unsaturated nitrogen can partake in directed aromatic or heteroaromatic lithiations. Pyrazole (II,D), tetrazole (II,G,2), imidazoline (V,B,2), and pyridine (IV,A,4) derivatives were discussed in the sections indicated. In addition, lithio derivatives of 2-oxazoline 178 (76LA183), 4,4-dimethyl-2-oxazoline 179 (790R1 85T837),... 

The Ugi group has designed a new class of convertible isocyanides, namely alkyl 2-isocyano-2-methylpropyl carbonates [7], prepared from commercially available 4,4-dimethyl-2-oxazoline. The Ugi-4CR of 11 afforded the expected products 12, which were converted into N-acyl a-amino acid esters 13 and N-acyl a-amino acids by in situ hydrolysis (Scheme 2.5) [7]. 

Methoxyphenyl)-4,4-dimethyl-2-oxazoline Dibromethane p-bromo trifluoromethylbenzene... 

This oil was redissolved in 300 mL dichloromethane, washed once with 100 mL water and once with 10 mL saturated sodium chloride solution, dried and concentrated under reduced pressure. The resulting residue was distilled under reduced pressure (0.040 mm, 95.degree.) to yield 2-(4,4-dimethyl-2-oxazoline-2-yl)-4 -trifluoromethylbiphenyl, yield 33%. A sample was recrystallized from 30-60°C petroleum ether (melting point 50-51°C). 

A solution of 2-(4,4-dimethyl-2-oxazolin-2-yl)-4 -trifluoromethylbiphenyl (3.5 g, 0.011 mole) in 60 mL 6 N hydrochloric acid was stirred at vigorous reflux for 2 hr. The reaction mixture was then cooled to room temperature and extracted with methylene chloride. The organic extracts were dried and concentrated under reduced pressure to yield a solid. Recrystallisation from ethyl ether/pentane afforded 4 -(trifluoromethyl)-2-biphenyl carboxylic acid, yield 86% (melting point 167-169°C). 

Some variants of our central reaction have been discovered. Consistent with the notion that NHC ligands are stable in the absence of aromatic jr-stabilization, a non-aromatic N-heterocycle, 4,4-dimethyl-2-oxazoline (3), can be added to olefins in the presence of a rhodium catalyst [10]. The optimized reaction conditions are especially mild, making this an effective method for preparation of protected carboxylic acids. 

Olefins react with 4,4-dimethyl-2-oxazoline (3) much more efficiently (Table 3, azoline column) than they do with other (aromatic) substrates [10]. Rather than requiring reaction temperatures of 135-180 °C for the reaction to occur, addition of 3 to olefins is optimally conducted between 45 and 105 °C. The substrate scope of this reaction includes, for the first time, disubstituted alkenes (Table 3, azoline column, Entries 2 and 3). The coupling products of 3 with olefins can be depro-tected to reveal carboxylic acids or elaborated further using well-known methods [16]. 

Hexyl-4,4-dimethyl-2-oxazoline (Table 3, Azoline column, Entry 1)... 

Other stabilized carbanions suggested to react via the SRN1 process include the anions from 2,4,4-trimethyl-2-oxazoline, 2-benzy]-4,4-dimethyl-2-oxazoline, 2,4-dimethylthiazole, 2-benzyl-4,4-dimethylthiazole, and dimethyl methylphospho-nate [25]. Some examples are described in Scheme 10.13. Competition with a benzyne process has been determined in some of these reactions. 

Coupling of R Br(Cl) with R2SnBu. 2 Alkyl halides couple with 2-(tributyl-stannyl-4,4-dimethyl-2-oxazoline (2) in the presence of this Pd catalyst (equation... 

There s no way -CH3 I can cover the complete naming system for organic compounds here but maybe what I ve presented will take the edge off when you see a molecule called 2-alkyl-4 4-dimethyl-2-oxazoline. Of course scientists never make things easy so you ll still see compounds called by their prefix naming convention. For example, we don t use the lUPAC system in naming isopropyl alcohol. 

Table 1-7. Catalyst effect on the Grignard (p-tolylmagnesium bromide) coupling with 2-(methylthio)-4,4-dimethyl-2-oxazoline (data from [112])...

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