Hydrolysis compounds

These reactions do not bring a direct peroxidation of ester into play, but rather of the compounds present (methanol) and of the hydrolysis compounds. 

Diels-Alder reactions of 2-(trimethylsilyloxy)allylidenecyclopropane (112) with electrophilic dienophiles gives 3-silyloxy spiro[2.5]oct-2-enes or the corresponding hydrolysis compounds spiro[2.5]octan-3-ones (Tables 11 and 12) [32]. 

Irradiation of the enol acetate (38) gave pure tricyclic acetoxyketone (39) in quantitative yield 17 -18). On alkaline hydrolysis, compound (39) was converted to the intramolecular de Mayo reaction product (40) in 78% yield 17,18). Epi-precapnella-diene (41) was obtained by further reactions of compound (40)19>. 

In base-catalysed hydrolysis, compound (93 R1 = R2 = Ph) behaves differently to (93 R1 = Me or Ph, R2 = OMe) not only with respect to reaction rate but also... 

Acids and Bases Forms of Ions in Aqueous Solution Ion Hydrolysis Compound Solubility... 

Combining substrate-induced diastereoselection and mutual diastereoselectivity, as illustrated for the crotylzincation of the alkenyllithium derived from 209, led to excellent results as the gewt-dimetallic species 217 was obtained in a highly stereoselective fashion. The stereochemical outcome was explained by the addition of the kinetically reactive cisoid metallotropic form of the crotylzinc reagent anti to the propyl group in the chelated allyl alkenylzinc intermediate. After hydrolysis, compound 218 was obtained as a single diastereomer (equation 106)148,149. 

Since the Si—O—C bond is sensitive to hydrolysis, compounds 150b-154b and their derivatives decompose under physiological conditions (Tyrode s solution pH 7.4 37 °C) by the action of water, forming the corresponding silanols and amino-alcohols [Eq. (22)] ... 

Hydrolysis. Compounds that possess an electrophilic atom (electron-poor) have a tendency to undergo hydrolysis reactions with electron-rich water or hydroxide ion (OH-). The reaction... 

Compound 48 is dissolved in ether at —20 °C, and an equivalent amount of Br2 (dissolved in pentane) is added. Reaction readily occurs. If temperature is controlled, side reactions such as bromination of the ether or cleavage of the Si-phenyl group can be excluded almost completely. After hydrolysis, compound 49 can be distilled off. Reaction (39) is easily achieved with Li powdered. 

The structure elucidation of 34 was based, in principle, on two facts color reactions and hydrolysis. Compound 34 does not react with ninhydrin (therefore, no primary amino group is present) but it does react with l-fluoro-2,4-dinitrobenzene. By exact determination of the absorption ratio E35O/E390 after the reaction with the latter reagent, Tait concluded that 34 contains a secondary amino group (50). Hydrolysis (6 N HC1, 110°C, 24 hr) of the so-called compound II afforded 2,3-dihydroxybenzoic acid and spermidine (50). The presence of two 2,3-dihydroxybenzoyl residues in 34 was demonstrated by its enzymatic (50) and chemical synthesis (51-54). 

Compound 19 was synthesized starting from 17 and 18 by tbe Suzuki reaction ([Pd(PPh3)4], Na2C03) as a 2 1 mixture of atropisomers (84 % overall yield) in which the natural (5)-dia-stereomer predominated. By introduction of the azido function under inversion of the configuration followed by ester hydrolysis, compound 19 was finally obtained. 

Typical of iV-sulfinylamino compounds, 100 functions as a dieno-phile in the Diels-Alder reaction and affords the cycloaddition product 101 op reaction with butadiene. On hydrolysis compound 101 is cleaved at the N—S bond with the resultant formation of (d -A-butenyl)-3-amino-l,2,5-thiadiazole (102). 

A water soluble activated ester of methoprene (Figure 5, Structure 16) was also prepared from sodium l-hydroxy-2-nitro-4-benzene sulfonate (16). The amount of compund 16 in crude preparations which contained both compound 16 and the free dianion (Figure 5, Structure 17) was determined by spectrophotometry in aqueous solution. Upon hydrolysis compound 16 yielded the dianion (Structure 17) which absorbed visible light at 406 nm in the presence of nucleophiles (Figure 5). Two absorbance readings were required to determine the amount of compound 16 present in the crude material. 

Polar head exchanges rely on the wide substrate specificity of PLD from bacterial sources. From low molecular weight primary alcohols to large secondary ones, many structurally diverse compounds have been shown to be substrates for PLD with different yields and selectivity (path c). The hydrolysis compound phosphatidic acid (PA) will be present as a by-product. 

R R = H/Pr", H/Bu", H/CHjNMej, H/Ph, H/COjEt, Me/Me, Me/COjMe, Ph/C02Et, Ph/CX OPh, C02Me/C02Me. In some cases of asymmetrical alkynes, the other isomer (8) also forms. The preference for position 3 increases in the order H < C02Et < Ph < alkyl (Equation (2)). The products are remarkably stable both to oxidation and hydrolysis. Compound (7), R = Me, R = H, R = Ph, taken as an example, does not react with elemental sulfur or methanol or both of them (typically a reactive combination towards other azaphospholes) <86CB4io>. 

The second method uses the pregnane derivative XI as a starting material. This compound, on hydroxylation with osmium tetroxide, afforded the diol Xlla. This diol was then converted to the androstane analogue X. The same approach was independently published also by Hondo and Mori (3). As a by-product of hydroxylation of olefin XI with osmium tetroxide, we obtained 2B,3B-diol XIV and, from this, the lactone XV. However, when we treated XII (a corresponding diacetate, respectively) with trifluoroperacetic acid we found that oxidation of the side chain surprisingly proceeded much faster than oxidation of the B ring. Thus we obtained not only compound X but also an intermediate, compound XHIb, and on hydrolysis compound Xllla, that is the androstane analogue of castasterone ... 

Acid hydrolysis compounds 105 Aminoacetophenone in wines 149 Anthocyanin derivatives 200 Anthocyanidins 164 Aroma compounds in grape 97,103,107... 

---