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Ketones, 3-amido preparation

The C=C bond in a 5-(alkylidene)oxazoline 644 is activated for electrophilic reactions similar to that in analogous vinyl acetates. Rohm Haas researchers exploited this property to prepare chloromethyl ketone fungicides 646 (Scheme 8.203). The overall process constitutes an indirect chlorination of a-amido ketones since the 5-(vinylidene)oxazolines were prepared from a-amido ketones. [Pg.509]

A further formal total synthesis95 of aspidospermine is provided by a new preparation of Stork s tricyclic amido-ketone (152). The hydrolulolidine system in (152) was neatly constructed by cheletropic expulsion of sulphur dioxide from the amide-sulphone (153), followed by an internal Diels-Alder reaction. [Pg.181]

Brossi and Wenis have prepared halfordinol (16) by cyclodehydration of the a-amido ketone 60 followed by hydrolysis of the intermediate O-benzyl derivative 61 (24). [Pg.269]

The ( )-tricyclic lactam ester 39, yet another emetine precursor (34), was also prepared by Takano s group (32,33,35) from ( )-norcamphor (74). Baeyer-Villiger oxidation of ( )-74 and subsequent ethylation yielded the ( )-lactone 75, which was then condensed with 3,4-dimethoxyphenethyla-mine and oxidized. The resulting ( )-ketone 76 was cleaved through the ( )-thioketal 77 to afford the ( )-amido acid 78. Exposure of ( )-78 to Mel... [Pg.11]

A wide variety of substituents are tolerated. The group R can be alkyl, halogen, alkoxy, -amido, azi-domethyl, ester, aryl, aryloxy and aryloyl, and at least one ortho substituent is permissible with no loss in yield. TTie aromatic ring can also be 2-naphthyl, 9,10-dihydro-2-phenanthryl, 3-pyridyl, thiophen-2-yl or pyrrol-3-yl. The group R can be hydrogen, yl, acyl or acetic acid. Beyond Ae antiinflammatory targets, successful reaction substrates include the methyl ketones of a binaphthyl crown ether, a morphinane and a polyaromatic hydrocarbon. The preparation of ibuprofen methyl ester (38) is shown in equation (37) as a typical example. ... [Pg.829]

Katritzky, A. R., Fang, Y., Silina, A. Preparation of P-Amido Ketones and Aldehydes via Amidoalkylation of Enamines, Enol Silyl Ethers, and Vinyl Ethers. J. Org. Chem. 1999, 64, 7622-7624. [Pg.689]

The reactivity of the dialkyl complexes TiR2(LL)2 (LL = N,N -dimethylaminotroponiminato) has been widely studied. Reactions with CO and aldehydes or ketones afford unsymmetrical diolato complexes that convert to the corresponding vicinal diols after hydrolysis. CO and acetylene react to form the oxametallacyclopentene complex. Treatment with RNC yields the free imine and low-valent titanium species (Scheme 131). In the reaction with BucNC, free ButN=CMe2 is formed and the addition of benzaldehyde or benzyl reagents affords titanium diolato or enediolato complexes. Thiolato-alkoxo or amido-alkoxo titanium complexes can also be similarly prepared (Scheme 132).123-125... [Pg.377]

Capture of a nucleophile, usually halide, represents a second major pathway, leading to overall addition to the alkene double bond. Acylations of ethylene (conveniently by automatic gasimetric techniques) and simple alkenes often give mainly the chloroethyl ketones. - Nucleophile capture has been used to advantage in the preparation of 3-amido ketones by using nitriles as the reaction solvent (equation 1). ... [Pg.709]

Treatment of triterpenoid 3-ketones [as (105)] with ammonium acetate and sodium cyanoborohydride in methanol and subsequent acidification with hydrochloric acid gives a 90% yield of the 3/3- (106) and 3a- (107) ammonium chlorides in a ratio of ca. 2 1. A range of 3-amino/28-amido-derivatives of oleanolic and ursolic acids has been prepared. The use of n.m.r. and u.v. spectra to establish the configuration at C-18 of olean-12-en-ll-ones has been further exemplified. ... [Pg.127]

Similar in approach to linear methods discussed previously, the cyclodehydration of a-amido ketones is an alternative strategy for preparation of the oxazole nucleus. Treatment of the ketone with PPhs and I2 results in cyclization to provide the fully substituted oxazole nucleus in excellent yield. This strategy was recently used in the synthesis of oxazole-modified glycopeptides, designed to target two classes of arthritis-associated proteins. The oxazole was probed as a conformationally locked dipeptide mimic. [Pg.241]

From a disconnection perspective, the use of a-amido ketones is appealing for many functionalized imidazoles. However, it sometimes suffers from many steps and poor overall yields. Much development work has gone into the preparation of the amido-ketone. For example, the Merck group has published the preparation of substrates for cyclization using a Stetter-like multicomponent coupling reaction (MCR). ... [Pg.345]

After the excellent development work on the process to prepare the a-amido-ketone, the work was further stretched into the one-pot synthesis of imidazole. This method proved somewhat general and gave good yields of many 4,5-di-substituted imidazoles. ... [Pg.345]

The iridium amido complexes (255) without P ligands, prepared from (256) and (257) by methanol elimination in THF, showed excellent enantioselectivities and activities in the asymmetric hydrogenation of simple ketones to alcohols. ... [Pg.179]

The above in situ strategy was also applied to Schiff base substrates (in Ueu of aldehydes or ketones), affording azuidination products in fair yield, moderate dr, and outstanding enantioselectivity [44, 45]. The specific examples of benzyUdene transfer illustrated in Table 4 confirm that electron-poor (entry 1), electron-rich (entry 4), aliphatic (entry 2), and a,p-unsaturated groups are tolerated in the A-SES imine electrophiles. As shown in Scheme 17, the utility of the method was showcased in an unconventional preparation of paclitaxel side-chain 49 that ultimately begins with 3-furfural. The optically pure heterocyclic aziridine 48 was obtained as an inconsequential diastereomeric mixture by the trio of coordinated phase transfer, achiral rhodium, and chiral sulfide catalyses, albeit in the antipodal series (see ent-47) subsequent conversicm to the target amido ester was by way of standard manipulations [130]. [Pg.132]


See other pages where Ketones, 3-amido preparation is mentioned: [Pg.346]    [Pg.1143]    [Pg.87]    [Pg.119]    [Pg.186]    [Pg.245]    [Pg.597]    [Pg.103]    [Pg.79]    [Pg.292]    [Pg.32]    [Pg.739]    [Pg.205]    [Pg.69]    [Pg.176]    [Pg.77]    [Pg.287]    [Pg.163]    [Pg.26]    [Pg.61]    [Pg.20]    [Pg.36]    [Pg.524]    [Pg.660]    [Pg.304]    [Pg.436]    [Pg.292]    [Pg.130]   


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