13- Lactam spiro

Keywords cyclohexenone, inclusion complex, photocyclization, )9-lactam, spiro compound... 

The synthesis of p- or y-lactones, y-lactams, y,8-unsaturated 8-lactones or lactams, spiro-lactones or cyclopentenes are some examples of the wide... 

The mechanism for the conversion of the A -oxide (94) to the o-methylaminophenylquinoxaline (96) involves an initial protonation of the A -oxide function. This enhances the electrophilic reactivity of the a-carbon atom which then effects an intramolecular electrophilic substitution at an ortho position of the anilide ring to give the spiro-lactam (98). Hydrolytic ring cleavage of (98) gives the acid (99), which undergoes ready dehydration and decarboxylation to (96), the availability of the cyclic transition state facilitating these processes. ... 

Conversion of cephalosporin 71 to the imidoyl chloride, followed by treatment with base in the presence of DEAZD gives a novel spiro 0-lactam (72), again via nitrile ylid cycloaddition.116... 

Gheorghe et al. make use of sodium cyanoborohydride as a hydride source in the synthesis of 5-arylpiperidines <06OL1653>. Kellehar and Kelly report the formation of a spiro -lactam using sodium borohydride in the key reductive animation step <06TL3005>. 

Dimethyl-3-methylenepyrrolidine-2-thione, which reacts with nitrones regio- and stereoselectively at its exocyclic C=C bond to give only spirocy-cloadducts 116, behaves more complicatedly with nitrile oxides. The latter undergo 1,3-dipolar cycloaddition both to the exocyclic C=C and C=S double bonds with subsequent cycloreversion and formation of spiro-lactams 117 (281). 

Photolysis of nitro-steroids 225 yields the aci-nitronate at 254 nm131. This in turn gives various products, among them are ketone 226 and hydroxamic acid 227 (equation 105) which could be formed from the intermediate anions of the Af-hydroxyoxaziridines, with a possible participation of gem-hydroxynitroso transient (or its anion see Scheme 10). For comparison, IV-butyl spiro-oxaziridine 228 in ethanol is photolysed at 254 nm (equation 106) to give 7V-butyl lactam 229 (50%) and the ketone 230 (25%). The former process is a well-known photoprocess of oxaziridine131. 

Sebti S, Foucaud A (1984) Reaction des acyloxy-2 chloro-3 chloromethyl-2 propanamides avec I hydroxyde de potassium ou le fluorure de cesium en milieu heterogene synthese de spiro P-lactames. Tetrahedron 40 3223-3228... 

As part of our efforts to develop new efficient one-pot methodologies to access novel heterocyclic structures, we also reported an efficient synthesis of spiro[4,61-lactones and lactames by sequential multicomponent reaction/metal-catalyzed carbo-cyclizations from simple five-membered cyclic (3-ketoesters and (3-ketoamides,... 

Spiro lactam 15 (Scheme 9), a dipeptide mimic with C (/)<-+Na(/ + l) cyclization, was used to replace the Pro-Tyr segment of an immunogenic peptide. 69 Comprehensive conformational analysis led to the conclusion that a type-II p-turn conformation was adopted in solution. 

Keywords Biological activity Cholesterol absorption inhibitors Ketene-imine cycloaddition Spiroazetidin-2-ones Spiro-(3-lactams Synthetic intermediates (3-Lactamase inhibitors... 

This article aims to review the development in stereoselective synthesis of spiro-(5-lactams and their biological evaluation as well as applications in various fields. 

The synthesis of (5-lactams having a small fused ring is of interest since the large strain of the ring should substantially alter the reactivity of (5-lactams. Several approaches for the synthesis of spiro-[5-lactams have been described in literature. 

Bose et al. [74] have investigated the novel synthetic route for the preparation of spirobarbiturates-a class of compounds known for their interesting physiological activity. The synthesis of spiro-fi-lactams 3 (Scheme 1) was achieved by the reaction of 4,4-dicarboxy-/V-phenylazetidin-2-one 1 with carbodiimides 2 in tetra-hydrofuran. 

Moricini and Kelly [75] have reported the synthesis of spiro-fi-lactams 6 containing an exocyclic double bond (Scheme 2) by the 1,2-dipolar cycloaddition of symmetrically/unsymmetrically substituted allene 4 with chlorosulfonyl isocyanate 5 in ether. 

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