Propiophenone derivative

Based on a similar literature method,116 stereoselective coupling reactions between various 3-acetoxy-4-alkyl-/3-lactams and in situ-generated titanium enolates of cyclohexanone117 or propiophenone derivatives were developed, yielding the corresponding a,/3-disubstituted /3-lactams. 

The dehydrogenation of (E)- and (Z)-w-piperidinopropiophenone oximes 272 and 273 with mercuric acetate-EDTA was investigated by Mohrle and Schmidt (82AP1032). From the reaction mixture of Z isomer 272, Z and E isomers of l-(3-hydroximino-3-phenylpropyl)-2-piperidone 275 and 276 and dimerized product 274 were isolated in 18% trace, and 24.8% yields, respectively. With six oxidation equivalents, E isomer 272 gave bicyclic products 278 and 279 and propiophenone derivatives 275, 276, and 111 in 9.3%, 16.4%, 4.1%, 18.1%, and 8.1% yields, respectively. When the reaction was carried out with four equivalents of oxidation agent, the N-oxide 279 was isolated in 44% yield. Oxidation of piperidino-... 

By-products can be formed in the synthesis of phosphines 263 with the iodome-thylatcs of ferroccnyl Mannich bases, as they tend also to give phosphonium salts 267 in amounts that depend on the duration of the reactionFurthermore, in the reaction with arsines, due to the reducing properties of such reagents, hydrogenolysis of the CH2—N bond may occur with the formation of a propiophenone derivative instead of the expected product 263 (X = As). 

Lewis Basic Phosphoramides. In a series of elegant investigations, Denmark has documented an aldol process that utilizes trichlorosilyl enolates such as 101 and 105 in catalytic, enantioselective addition reactions (Eqs. (8.28) and (8.29)) [45]. These unusual enoxysilanes are prepared by treatment of the corresponding tribu-tylstannyl enolates with SiCl4. Trichlorosilyl enolates are sufficiently reactive to add to aldehydes at -78 °C, but their addition can be substantially accelerated by the addition of Lewis basic phosphoramides. The use of catalytic amounts of chiral phosphoramides leads to the formation of optically active products. Thus, treatment of the cyclohexanone or propiophenone-derived trichloroenolsilanes 101 and 105 with a variety of aldehydes afforded adducts displaying high levels of simple diastereoselectivity and up to 96% ee. On the basis of the stereochemical outcome of the reaction, Denmark has postulated that the reaction proceeds through an or-... 

Furthermore, the diasteroselectivity observed using catalyst (S,S)-62 depends on the nature of the latent trichlorosilyl enolates. Thus, propiophenone-derived enolate 65 possessing the Z-configuration reacts with benzaldehyde in presence of 15 mol% of (SyS) 62 to afford the syn adduct 66 with very high enantioselectivity. 

Tidwell and coworkers have estimated from structure-reactivity relationships that the ft -dimethylenamines are slower by a factor of 30 than if the -methyl groups were absent. Similarly, the single S-methyl group on the propiophenone derivatives is expected to reduce h+ by a factor of 3.4 . ... 

The pyrazole synthesis described in equation (34) has been extended in a number of ways by Beam s group. Starting with unsubstituted hydrazones of various acetophenone and propiophenone derivatives, deprotonation with 3 equiv. of Bu"Li leads to trianions that can be condensed with an ester and subsequently cyclized with acid to yield pyrazoles containing N—H groups (as opposed to N—Ar groups in... 

Fig. (53). Structure of a propiophenone derivative isolated from Baccharis magellam ica...

In order to overcome the tricky regioselectivity problem, hydroformylation of the corresponding enol ethers has been suggested (Scheme 6.67) [181]. These substrates are accessible via acetalization of a relevant propiophenone derivative, followed by elimination of 1 equiv ethanol. The hydroformylation reaction with a rhodium cluster was performed in a 100 g scale. The enolether reacts in the P position. A second elimination step afforded the a,p-unsaturated aldehyde, which was reduced with H2 to give selectively the desired 2-formyl compound. 

In 2007, Matsubara and coworkers developed an active, easy-to-prepare, and stable nickel catalyst by incorporating an NHC as the stabilizing ligand (Figure 8.4). Efficient a-arylation of a number of propiophenone derivatives could be achieved using 10 mol% of this catalyst to afford the desired products in moderate to good yields (Scheme 8.76) [61],... 

Lectka and coworkers took advantage of the high electrophilic reactivity of the carbon-nitrogen double bond in the AT-tosyl imino ester 340 and studied enantioselective additions of ketone-derived silyl enol ethers 220, mediated by (7 )-To1-BINAP-CuC104 (341). The loading of ligand and metal salt could be reducedto 2 mol%. Keto esters 342 were thus obtained in high chemical yields and enantiomeric excess, which could be increased to 99% ee after recrystallization (Scheme 5.92) [175]. The protocol was extended to propiophenone-derived... 

The utility of aqueous [ C2]acetaldehyde is illustrated by its Homer-Wadsworth-Emmons olefmation with diethyl (cyanomethyl)phosphonate under phase transfer conditions to give [3,4- C2]crotonitrile (16) in 83% radiochemical yield. Subsequent Michael addition of a-aminonitrile 17 produced the masked y-ketoacid derivative IS (Figure 8.6), which served as a key intermediate in the synthesis of [ " C2]C1930 (19). For the TiCLi-promoted aldol reaction with the propiophenone derivative 20, however, the use of anhydrous [ 2] acetaldehyde was essential. The reaction proceeded with excellent stereoselectivity, providing exclusively the racemic syn-diastereomers 21. Subsequent... 

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