Acrylic esters, phenylation

The enamines derived from cyclic ketones give the normal alkylated products, although there is some evidence that unstable cycloadducts are initially formed (55b). Thus the enamine (28) derived from cyclohexanone and pyrrolidine on reaction with acrylonitrile, acrylate esters, or phenyl vinyl sulfone gave the 2-alkylated cyclohexanones (63) on hydrolysis of the intermediates (31,32,55,56). These additions are sensitive to the polarity of the solvent. Thus (28) in benzene or dioxane gave an 80% yield of the... 

However, most asymmetric 1,3-dipolar cycloaddition reactions of nitrile oxides with alkenes are carried out without Lewis acids as catalysts using either chiral alkenes or chiral auxiliary compounds (with achiral alkenes). Diverse chiral alkenes are in use, such as camphor-derived chiral N-acryloylhydrazide (195), C2-symmetric l,3-diacryloyl-2,2-dimethyl-4,5-diphenylimidazolidine, chiral 3-acryloyl-2,2-dimethyl-4-phenyloxazolidine (196, 197), sugar-based ethenyl ethers (198), acrylic esters (199, 200), C-bonded vinyl-substituted sugar (201), chirally modified vinylboronic ester derived from D-( + )-mannitol (202), (l/ )-menthyl vinyl ether (203), chiral derivatives of vinylacetic acid (204), ( )-l-ethoxy-3-fluoroalkyl-3-hydroxy-4-(4-methylphenylsulfinyl)but-1 -enes (205), enantiopure Y-oxygenated-a,P-unsaturated phenyl sulfones (206), chiral (a-oxyallyl)silanes (207), and (S )-but-3-ene-1,2-diol derivatives (208). As a chiral auxiliary, diisopropyl (i ,i )-tartrate (209, 210) has been very popular. 

As exemplified in Eq. 8.38, thermal [2 + 2] cycloadditions of 4-vinylidene-2-oxazoli-dinone 287 and alkynes such as phenylacetylene result in the formation of 3-phenyl-substituted methylenecyclobutene 288 [149]. The authors confirmed by NMR analysis that only the Z-configuration isomer was formed. It is worth noting that the [2 + 2] cycloaddition of allenes 287 is not restricted to alkynes even olefins such as acrylic esters or silyl enol ethers furnish the corresponding methylenecyclobutanes... 

Phenylation of styrene, acrylic esters, and acrylamide with Ph3Bi(02CCF3)2 was examined using palladium nanoparticles immobilized in spherical polyelectrolyte brushes (Pd SPB) (Scheme 7) [21], The reaction can be conducted under air, and... 

Another reaction which occurs readily in solid polymers is the Fries reaction which can be observed in phenyl esters, particularly in phenyl acrylate and phenyl methacrylate polymers. The course of the reaction can be followed very... 

The triazolines formed from aryl azides and a,]8-unsaturated esters or ketones can be opened by bases to a-aminodiazo compounds. Methyl acrylate and phenyl azide thus yielded ethyl 2-diazo-3-phenylaminopropionate (106)... 

Greenhouse evaluation in a random herbicide screen showed that 3-chloro-4-methyl-6-[m-(trifluoro-methyl)phenyl)pyridazine was sufficiently active to serve as a lead for a synthesis project. Related 3-chloropyridazines were prepared by a sequence based on the addition of acyl anion equivalents of substituted benzaldehydes to the appropriately substituted acrylate esters. Using 3-chloro-pyridazines as key intermediates, a variety of other 3-substituted-pyridazines were prepared. The effect of altering substitution at each position of the pyridazine and phenyl rings on herbicidal activity was examined. 

Active methylene compounds can be added to polar double bonds such as those in acrylate esters and methyl vinyl ketone as has been described in the previous section. Active methylene compounds can also be added to carbon-carbon multiple bonds in allenes and alkynes with the aid of the transition metal complexes as the catalyst. The addition of methylmalononitrile to 3-phenyl-l,2-butadiene takes place in the presence of Pd2(dba)3-CHCl3 to give the corresponding addition product with E-stereochemistry (Eq. 67) [137 a]. The C-C bond formation occurs exclusively at the terminal position of the allenes. Trost et al. independently reported the similar results with respect to palladium-catalyzed addition of C-H bonds in active methylene compounds to allenes [137 b. ... 

Contrary to acrylic esters or acrylonitrile, a vinyl ketone could be polymerized with aluminum (or zinc) alkyl alone in the absence of any added Lewis bases. The mechanism of polymerization of phenyl vinyl ketone(PVK) was studied by using a model initiator, ethylzinc-1,3-diphenyl-l-pentene-l-olate (ZC), which possessed the same structure (see below) as the growing chain end in zinc alkyl-initiated polymerization of PVK (12). 

The muscle relaxant Pirindol (13) invites disconnection of both phenyl groups to give ester (14), easily made from piperidine (15) and an acrylate ester. 

The case of azides is the one where the difference of orientation according to the polar character of Y is best defined These 1,3-dipoles behave as if they had a stable polarisation in the sense Ar-N-N=l, the nitrogen atom on the left receiving electrophilic attack by acrylic esters and acrylonitrile, the terminal atom nucleophilic attack by enamines and vinyl ethers. While it has been argued that the main factor controlling orientation in 1,3-cycloadditions to olehns and acetylenes is a steric one", phenyl azide can add in the usual orientation even to a bulky enamine viz-... 

Disubstituted acetylenes and 1,2-disubstituted olefins are comparatively bad dipolarophiles. If the introduction of the second substituent was expected to have a strong accelerating effect, this is lacking (fumaric ester is sometimes less reactive than acrylic ester) or is small, c.f. acetylene dicarboxylate with propiolates. When the second substituent is a phenyl group, it deactivates phenylpropiolate is less reactive than propiolate in reaction types (i) (ii) and (iv). Table 13. The introduction of methyl groups into the a or )3 position of acrylic ester, has a similar effect on the rate of several different 1,3-cycloadditions". Steric hindrance appears to intervene in these cases. 

Sect. 4.4. These results explain satisfactorily the catalytic formation of 8-phenyl-hexahydromethanotriphenylene reported by de Meijere [47]. The precursor of the final product of Scheme 6 was also trapped by adding an acrylic ester (Eq.40) [48]. 

The photocycloaddition of 2tf-azirines to electron-deficient olefins produces d -pyrrolines as primary photoproducts. Some of the dipolarophiles used include acrylic esters, acrylonitriles, fumaric and maleic esters, methyl allenecarboxylate, norbornene, and l,2-dicyanocyclobutene. Similarly, styrenes and vinylpyridines undergo smooth photocycloaddition to 2H-azirines. Addition of acetylene derivatives to the transient nitrile ylide gives 2H-pyrroles (18, 20) which rearrange to pyrroles (19) if the C-2 atom is monosubstituted. 3-Phenyl-2/f-azirines have been found to cycloadd to vinylphosphonium salts and to vinyl sulfones. The initial adducts (22 and 24) undergo ready loss of the phosphorous or sulfur substituent to give 2H-pyrroles (23 and 25). ... 

Two significant communications have described the generation of glycosyl radicals by treatment of glycosyl bromides or phenyl 1-selenoglycosides with trlbutyltln hydride, and their trapping with acrylic esters or acrylonitrile. Good a-selectivity was observed with yields of specific adducts of up to 70% (Scheme 15). ... 

Vinyl carbanions derived from acrylic esters and their jS-phenyl derivatives react with several carbon electrophiles to give a-substituted and a,/8-disub-stituted derivatives. While /8>alkyl substituted acrylates have been shown to dimerize in the presence of potassium catalyst at 110 C. Three simple unsaturated esters undergo palladium(0)-catalysed codimerization with methylenecyc-lopropane to furnish methylenecyclopentanecarboxylic esters in reasonable yield. An efficient procedure for the oxidation of isatins to anthranilic acid esters has appeared. Methyl 2,4,6-tri-isopropylbenzoate forms a dipole-stabilized carbanion on reaction with Bu Li, which then reacts with carbon electrophiles [e.g. E = Bui, (CH3)2C0, or CH3CHO] to give a range of ester derivatives in good yield (Scheme 52). ... 

Rate constants ( 2) for cycloadditions of phenyl azide to substituted ethylenes and acetylenes stretch over seven magnirndes high values were observed for enamines, moderate k2 for the acrylic ester type, and the rate minimum was found for common alkenes and alkynes (Huisgen, Szeimies, Mobius, 1967). hi the PMO treatment of concerted cycloadditions, Reiner Sustmann found the key to the understanding of substituent effects e.g., a plot of k2 for the cycloadditions of Ph-Ns versus the ionization potential of substituted ethylenes and acetylenes furnished a degenerate U shape (1971). Such a plot is a distinguishing feature for each 1,3-dipole and reflects the specific mix of nucleophilic and electrophilic activity, modified by steric effects. 

Doubly deprotonated methyl 3-nitropropanoate is also useful for the synthesis of a-substituted acrylic esters. These compounds are prepared in good yield from substituted diethyl malonates by alkylation with 1-chloroethyl phenyl sulphide followed by dealkoxycarbOnylation. P-Substituted acrylic esters are readily prepared from the a-cyano-enamine (110) (Scheme 65). ... 

The 2-phenyl-2-ethyl-pentane-1,5-diacid-mononitrile-(1) of melting point 72° to 76°C, used as starting material in this process, can be produced for example from o-phenyl-butyric acid nitrile by condensation with acrylic acid methyl ester and subsequent hydrolysis of the thus-obtained 2-phenyl-2-ethyl-pentane-1,5-diacid-monomethyl ester-mononltrile-(l) of boiling point 176° to 185°C under 12 mm pressure. 

It is supposed that the nickel enolate intermediate 157 reacts with electrophiles rather than with protons. The successful use of trimethylsilyl-sub-stituted amines (Scheme 57) permits a new carbon-carbon bond to be formed between 157 and electrophiles such as benzaldehyde and ethyl acrylate. The adduct 158 is obtained stereoselectively only by mixing nickel tetracarbonyl, the gem-dibromocyclopropane 150, dimethyl (trimethylsilyl) amine, and an electrophile [82]. gem-Functionalization on a cyclopropane ring carbon atom is attained in this four-component coupling reaction. Phenyl trimethyl silylsulfide serves as an excellent nucleophile to yield the thiol ester, which is in sharp contrast to the formation of a complicated product mixture starting from thiols instead of the silylsulfide [81]. (Scheme 58)... 

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