Lactams acids

The mechanism of acid hydrolysis is also different in acyclic amides and /1-lactams acid catalysis of acyclic amides proceeds via O-protonation (see Chapt. 4), whereas that of /1-lactams appears to be a unimolecular A1 type process, involving V-protonation (Fig. 5.6,b) [76], A-Protonation is not the result of reduced amide resonance but an intrinsic property of the /1-lactam structure, since bicyclic /1-lactams and monocyclic /1-lactams exhibit similar reactivity and behavior [76],... 

The production of lactamic acid alanin), and that of lactio acid from the latter by the action of nitrous add, are tdso dearly confirmatory of the above view. 

A large number of compounds used as catalysts in acid-ion lactam polymerization are known. These include alkalis, alkali-earth metals, hydrates, Grignard reagents, lithium oxide, various hydroxides and carbonates, sulfates, halides, sodium zincate, alkaline salts of different acids, i.e., compounds that cause the formation of lactam acid ion in the reactive medium. The mechanism of polymerization in the presence of sodium-lactam- salt compounds is largely known. 

X-Ray crystallographic structure determinations of several degradation products of lycoctonine, including the keto-lactam acid (3), have been reported.5 Chemical... 

At this temperature, after a few minutes, the lactam acid 3 suffers smooth decarboxylation to afford Ar-phenyl-2-pyrrolidi-none. Alternatively, the acid can be esterified (methanol-hydrochloric acid), and the resulting l-phenyl-3-carbomethoxy pyrrolidin-2-one can be used for the introduction of other functionality at the 3-position. 

Finally, X-ray crystallographic analysis of 0,0-dimethylipecoside (143), together with the knowledge that hydrolysis of ipecoside (19) produces D-glucose, has established its structure and absolute stereochemistry (7/5). The position of the double bond in the ( )-unsaturated lactam acid 144, a synthetic intermediate for the emetine precursor ( )-45, has been inferred from chemical and spectroscopic evidence (285) and confirmed by an X-ray study (286). 

The reaction of esters of methylenedioxyphthalic acid (387) with the imine (388) affords the ester-lactam (389) and hydrolysis of this to the lactam-acid followed by Arndt-Eistert homologation and cyclisation yields the ketone (390, R R =0). Reduction of this to the secondary alcohol (390, R =H, R =0H), followed by dehydration and aerial oxidation affords oxosangui-narine (391), from which sanguinarine can be prepared (Shamma and H. Tomlinson, J.org.Chem., 1978, 2852). A similar... 

IR and UV absorption spectroscopy of 6-chloro-2( 1 //j-pyridone acetic acid mixtures in carbon tetrachloride at room temperature indicated lactim-acid and lactam-acid heterodimer formations, preferential association being with the lactam tautomer. In the presence of acetic acid, the proportions of monomeric pyridone species diminish (80JCS(P2)620). 

Syntheses of ( )-canadine, ( )-thalictricavine, ( )-corydaline, and berlambine have been achieved from dimethoxyhomophthalic anhydride (88). The anhydride reacts with hydrastinine (87 R R = CH2) and its dimethoxy-analogue (87 R = r2 = Me) to give the lactam acids (89 R R CH2) and (89 R = R = Me) the methyl esters of which, on reduction with lithium aluminium hydride, yield the alcohols (90 R R = CH2, R = CH2OH) and (90 R = R = Me, R = CH2OH). The conversion of these alcohols into their methanesulphonyl esters, followed by reduction with sodium borohydride, then affords ( )-thalic-tricavine(90 R R = CHa,R = Me) and( )-corydaline(90 R = R = R = Me). Oxidation of the lactam acid (89 R R = CH2) with lead tetra-acetate and copper(ii) acetate in acetic acid and dimethylformamide gives the unsaturated lactam berlambine (91), which can be reduced by lithium aluminium hydride in the presence of aluminium chloride to ( )-canadine (90 R R = CH2, R" = H). ... 

The first stereoselective synthesis of ( )-dihydroantirhine (86) employs a neat device for stereochemical control, and proceeds in a remarkable overall yield of 40% from the lactam (87). Addition of the ynamine (88) to (87) involves preferentially a transition state in which ring d has a flattened half-chair, rather than a half-boat, conformation, which results in the formation of the intermediate (89). Proton addition to (89) during acid hydrolysis to the lactam-acid (90) occurs predominantly on the more accessible exo face the stereochemistry of (90), and thus of ( )-dihydroantirhine (86), is thereby assured (Scheme 11). ... 

Alangicine (132) has been synthesized from the acid derived from (129) by reduction and hydrolysis. This, with the appropriate /3-phenethylamine, gives the amide (131). The absolute stereochemistry of alangicine has been confirmed by its synthesis from ethyl cincholoiponate via the lactam acid (133). ... 

Various aspects of the chemistry of some 2fi"-l,4-benzothiazinehydrox-amic acids have been investigated. When refluxed in aqueous sodium hydroxide the hydroxamic acid (102) gives three products, two of which correspond to the lactam acid (103) and the unsaturated acid (104). The 6-methyl and 6-bromo-derivatives of (101) behave similarly, whereas the... 

Berberine-acetone when subjected to mild permanganate oxidation is converted to neoxyberberine-acetone and to the lactamic acid 43 reminiscent of Perkin s berberal. ... 

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