Hydrolysis opening

Hydrogen halides give iV-protonation of 2/7-1,2,3-diazaphospholes (molecular structure of a hydrochloride in Table 2) but also add to the P=C bond (see Section 4.22.5.1.2). Hydrolysis opens the P=N bond of l,2,3-diazaphospholo[l,5-a]pyridines <95S173>. 

Although no 4-aminoquinolizinium derivatives are known, a benzo derivative, 6-amino-acridizinium ion (72 Scheme 50), has been prepared (67JOC733). In the presence of hydroxide ion the amino group loses a proton to form a benzo[6 ]quinolizin-6-imine (73). Alkaline hydrolysis opens the ring to give the amide (74). 

Then acid hydrolysis opens up the cyclic ester, and decarboxylation follows ... 

The fact that a mixture of olefins is actually obtained, however, indicates that this cannot Ik the only mechanism of hydrolysis open to hydroxylated compounds. 

This structure is most commonly found as the monocarbonyl form (39), a hemiacetal which behaves as such. Hydrolysis opens the ring, whereas... 

In contrast, the intermediately formed methylenecyclopropane 44 reacts with electron-rich alkenes to give cycloadducts, e.g. 45, with the bis(acceptor)methylenecyclopropane reacting as a heterodiene. This hetero-Diels-Alder reaction is also applicable to electron-rich alkynes, e.g. formation of 46. Thus, a solution of 3-acetoxy-5,5-dimethyl-2-(l-piperidinocyclo-propyl)cyclohexen-2-enone (47) and 1 equivalent of alkyne was reacted at 36°C for 4 hours. Alkyl-substituted alkynes, although applied in great excess, did not form any products. Depending on the substituents, further acidic hydrolysis opens up a method for the preparation of acetates or lactones. 

Alkaline hydrolysis opens the lactone ring to form l-(2-hydroxyethyl)-5,6,7, 8-tetrafluoro-4-quinolone-2-carboxylic acid. 

Dissolving metal reduction cleaved the N-benzyl group and acid hydrolysis opened the lactam ring to give ethyl 3-amino-4-ethenylcyclohexane-l-carboxylate, 7.57.42... 

Structure was determined straightforwardly by n.m.r. techniques. Alkaline hydrolysis opened the lactone, thionyl chloride then gave the expected exomethylene compound. Toonacilin (80) (779) already has the lactone opened and has in addition an 1 la,12a-diacetoxy system. The structure of this substance was determined by x-ray crystallography. 

Figure 8, In vivo degradation of PVA by PVADH and OPHfrom Sphingomonas sp. strain I UPS. (a) Spectrophotometric analysis of oxidized PVA formation and hydrolysis. Open circle, in the presence of OPH, and open diamond, in the absence of OPH. (b) Absorption spectra of oxidized PVA formed in the reaction mixture, (c) HPLC analysis of molecular shift by hydrolysis of oxidized PVA solid line, oxidized PVA dashed line, hydrolyzed oxidized PVA. (Reproduced from reference 10. Copyright 2005 The Society for General Microbiology.)...

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