Alkoxy amides, hydrolysis

The dominance of an alkoxy group over a silyl group is manifested in the generation of amides from reaction of oc-silyl enol ethers with chlorosulfonyl isocyanate, followed by hydrolysis. Simple vinylsilanes and alkynylsilanes undergo carbamidation [34],... 

The ring of 4(5H)-oxazolones is readily opened under mild hydrolytic conditions, amides being produced (equation 40). Compounds possessing a 2-alkoxy substituent undergo hydration rather than hydrolysis to yield eventually 2,4-oxazolidinediones (equation 41). 

The resistance of the furoxan ring to chemical attack allows derivatives to be prepared via the reactions of the substituents (Section 4.22.3.4). Carboxylic acids are available by permanganate oxidation of methyl derivatives or by hydrolysis of the corresponding esters reaction with ammonia affords carboxamides. Acylfuroxans provide a source of hydroxyalkyl compounds by reduction, and oximes, for example, via nucleophilic addition. Acylation and oxidation of aminofuroxans allows the amide and nitro derivatives to be prepared. Nucleophilic displacements of nitro substituents can take place, but can be somewhat hazardous on account of the explosive nature of these compounds. Alkoxy derivatives are formed with sodium alkoxide, while reaction with thiolate anions yields sulfides, from which sulfones can be synthesized by peracid oxidation. Nitrofuroxans have also been reduced to... 

The alkoxy- and silyloxyiminium salts 81 and 84 are obtained from chiral acrylamides by heating with triethyloxonium tetrafluoroborate or trialkylsilyl triflate. These very active dienophiles add to cyclopentadiene (2) with excellent diastereoselectivity, generating norbor-nenyl amides after hydrolysis (see table below)22,23. The best results are obtained by triflate activation, while tetrafluoroborate activation generally leads to a mixture of products22. 

Hydrolysis of TEOS in various solvents is such that for a particular system kH increases directly with the concentration of H+ or H,0+ in acidic media and with the concentration of OH in basic media. The dominant factor in controlling the hydrolysis rate is pH (21). However, the nature of the acid plays an important role, so that a small addition of HC1 induces a 1500-fold increase in A, whereas acetic acid has little effect. Hydrolysis is also temperature-dependent. The reaction rate increases 10-fold when the temperature is varied from 20 to 45°C. Nmr experiments show that k-H- varies in different solvents as follows acetonitrile > methanol > dimethylformamide > dioxane > form amide, where the kH in acetonitrile is about 20 times larger than the kH in form amide. The nature of the alkoxy groups on the silicon atom also influences the rate constant. The longer and the bulkier the alkoxide group, the lower the kH (3). 

Interestingly, the cyclic ester (73) does not rearrange. A comparison of the hydrolytic behaviour of the esters (74) and (75) has shown that the presence of the triple bond generally increases the rate of hydrolysis under basic conditions. The hydrolysis of the fluorides R R P(0)F (R and R are alkyl or alkoxy) has been examined for both alkaline and neutral aqueous solutions. For the amides Ph2P(0)X (X = NMe2 or NHC6H4NO2-4), the increase in the rate of acid-catalysed hydrolysis in acetonitrile with decreasing concentration of water has been ascribed partly to an increase in the basicity of the substrate under the same conditions. ... 

In an attempt to perform an addition of an allyl anion to a reactive alkene, syn-1-allyloxynorbornene was treated with methyl-lithium. After hydrolysis (413) and (414) were obtained in the ratio 3 7. It is concluded that (413) does not arise by a concerted [2 + 4] cycloaddition of (410) followed by cleavage of the initial alkoxy carbanion (41IX but rather a stepwise process via (412) leads to the two products. Treatment of cycloheptatriene with potassium amide gives dimers (417) (70%) and (418) (14%). To determine whether the reaction involves addition of cycloheptatriene to cycloheptatrienyl anion (415) or to the adduct ion (416) the experiment was performed with 1,2,3,4,5,6-hexadeuteriocycloheptatriene. The isotope distri-... 

Alkoxy derivatives (ROOZLO) were polymerized by MeOTf via CROP mode since its polymerization yields polypeptide derivatives. The CROP of (S)-4-isopropyl-2-ethoxy-5-oxazolone (R=EtO, R = i-Pr) (Scheme 44) yields poly(N-ethoxycarbonyl-L-valine), which was converted to poly(L-valine) by basic hydrolysis. " Contrary to poly (L-valine), poly(N-ethoxycarbonyl-L-valine) is soluble in many organic solvents probably due to the lack of amide hydrogen bonding, which is expected to expand the availability of polypeptide derivatives. ... 

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