T-Butylhypochlorite

In the pyrrole series, ester groups a to nitrogen are more readily hydrolyzed by alkali, but those in a /3 position more readily by acid. A methoxycarbonyl group in the 2-position is meta directing thus bromination yields mainly 4-bromo-2-methoxycarbonylpyrrole. Free radical chlorination with t- butylhypochlorite gives the 5-chloro derivative. 

The sulfur-free analogs of penicillins and cephalosporins have attracted much attention of both synthetic and medicinal chemists, since the successful development of new 1-oxacepham antibiotics by the Shionogi group17 . Namely, oxazoline-azeti-dinone derivatives 19 have been used as key intermediates in the synthetic chemistry of new beta-lactam antibiotics 18). The compounds 19 have usually been prepared by a two-step operation involving the reaction of 79 with chlorine or t-butylhypochlorite followed by treatment with a base. 

Contrary to the 1-vinylcyclopropanol derivatives which easily underwent an acid catalyzed or thermally induced C3 -> C4 ring expansion as discussed in Sect. 5.1.1, the acetylenic cyclopropanols 9 were surprisingly unreactive towards acids. Thus, on heating for two hours to 55 °C in acidic (0.75N HC1) 50 % aqueous dioxane containing a catalytic amount of mercuric chloride or upon treatment with m-chloroper-benzoic acid (MCPBA) for 12 hours at room temperature, the alcohol 9 (R = H) was recovered unchanged. However, treatment of 9 with an alcohol free solution of t-butylhypochlorite (t-BuOCl) in chloroform resulted in an exothermic reaction which yielded 2-chloromethylenecyclobutanone 39 as the only isolable product, Eq. (13)10). 

First of all, it has been shown that the 1-vinylcyclopropanols 207 undergo ring expansion to cyclobutanones 209 with a large variety of electrophilic reagents. Thus, with hydrobromic and perbenzoic acid and with t-butylhypochlorite, 2-alkyl-, -2-hydroxymethyl- and 2-chloroalkylcyclobutanones 209, respectively, were obtained, through 1-hydroxycyclopropylcarbinyl cation intermediates 208 Eq. (65) 10,133). 

By reaction with t-butylhypochlorite in benzene, cyclohexylamine is converted... 

The formation of imidoyl chlorides in the chlorination of azomethines, using t-butylhypochlorite as the chlorinating agent, has been reported by Paul and his colleagues... 

Nylon can be rendered flameproof by the part replacement of imino H atoms with phosphinyl groups. This is done by chlorination with t-butylhypochlorite, followed by treatment with trialkyl phosphite (12.221). 

Ganem has described a novel allylic alcohol to haloepoxide transformation (26) (28) using t-butylhypochlorite as the oxidant. This is the first known case where anchimeric participation by the hydroxyhalonium ion, as in (27), is invoked. The reaction, which has an analogy with iodolactonization, is susceptible to conformational and stereochemical requirements, since the octalin (29) gave a low yield of (30). Mild conditions for the preparation of (mostly steroidal) oxirans... 

Isothiazol-3-ones (366) have been obtained in 92% yield by thermolysis of 2-ethoxy-3-cepham-lj8-oxide (365) in ethyl acetate. The latter was derived from the cephem (363), which gave the oxazoline (364) with t-butylhypochlorite. ... 

A synthesis of acylenamino carboxylic acids from acylamino acids has been described by Poisel and Schmidt 310,312,313). Acylamino acid esters are N-chlorinated with t-butylhypochlorite in the presence of catalytic quantities of base. A full equivalent of base can then be used to eliminate HCl, with the initial formation of acylimino esters as unstable primary products which then either add solvent (alcohol) to form a-acylamino-a-alkoxy acid derivatives (22), or (in the absence of protic solvents) rearrange to the acylenamino acid esters (21). The a-acylamino-a-methoxy carboxylic acid (22) esters can also be converted... 

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