Le Thanh Giang

Simple and condensed β-lactams. Part 27. Reaction of 1-(4-methoxyphenyl)-4-(tetrazol-5-yl)azetidin-2-one and 1-(4-methoxyphenyl)-5-(tetrazol-5-yl-methyl)pyrrolidin-2-one with cerium(IV) ammonium nitrate (CAN)☆

Abstract Treatment of pyrrolidinone 3a with CAN under the usual conditions leads to formation of spiro compound 12, rather than to N-demethoxyphenylation. A study of the reactions of compound 12 with sodium chloride and sodium iodide furnished the proof for our assumption that the related non-isolable compounds 6 and 11 are the intermediates of the anomalous reactions of compounds 1a and 2a, respectively, with CAN.

Oxidative cyclization by lead(IV) acetate of 1-(4-methoxyphenyl)-4-(tetrazol-5-ylmethyl)azetidin-2-ones to 3-methoxy-9,9a-dihydroazeto[1,2-a]tetrazolo-[5,1-d][1,5]benzodiazepin-11(10H)-ones and related reactions

Abstract The tetrazolyl groups of azetidin-2-ones 1a-e and 1h interfere with the normal reaction of related azetidin-2-ones with lead(IV) acetate, viz. acetoxylation at C-4, and cause formation of tetracyclic products 3a-e and 3h. Similar reactions take place with ring homologues 1f, 1g and 1i, and with open-chain analogues 11a and 11b.

Simple and condensed β-lactams. Part 20. Reaction of some 1-(4-methoxyphenyl)azetidin-2-ones with cerium(IV) ammonium nitrate (CAN): Trapping of the quinone imine intermediate with chloride and iodide anions

Abstract 1-(4-methoxyphenyl)azetidin-2-ones 12 and 13, when treated with cerium(IV) ammonium nitrate (CAN), afford either their N-deprotected derivatives (19, 26) or the chlorinated compounds 22 and 27, respectively, as the main products, depending on whether sodium chloride was present or not. A series of minor products (20, 21, 23–25 and 29, respectively) are formed in addition. 1-(4-Methoxyphenyl)azetidin-2-ones 13 and 14, when treated successively with CAN and sodium iodide, afford the corresponding 1-(4-hydroxyphenyl)azetidin-2-ones 28 and 30, respectively, in good yields. The latter reactions could possibly form the basis for elaboration of a potentially general method for dealkoxy-hydroxylation of N-(2- and 4-alkoxyphenyl)carboxamides. Mechanisms are suggested for the formation of compounds 19 – 30.

Oxidative fragmentations of some azolyl ketones and related compounds induced by cerium (IV) ammonium nitrate (CAN)

In contrast to simple ketones which are stable to CAN, azolyl ketones 3d–3f, 11a, 11b and, in part, 3c and 4c undergo oxidative fragmentation when treated with cerium(IV) ammonium nitrate (CAN).

Oxidative cyclization of some 1-aryl-5-(tetrazol-5-ylmethyl)pyrrolidin- 2-ones and of a related piperidin-2-one. Preparation of fused tetracyclic tetrazolobenzodiazepinone derivatives

In contrast to compounds of type 1a, compounds 1c–1i, when treated with lead(IV) acetate or cerium(IV) ammonium nitrate, underwent oxidative cyclizations to afford the corresponding compounds of type 3 with both oxidants, while oxidation of compound 1p afforded compound 2a (m = n = 1).

Studies into the synthesis of azolopyrrolidinobenzodiazepinones and related compounds. Oxidative cyclisations, oxidative fragmentations and oxidative rearrangements in the reactions of azolylmethyl-N-phenyl-lactams and related compounds with cerium (IV) ammonium nitrate

Depending on the nature of the bridge connecting the two hetero rings of the substrates of types 4, 7, 11 and 12 studied, the substrates are attacked by CAN at different sites and, therefore, afford different types of oxidation products.

The reaction of 2-(tetrazol-5-yl)alkyl ketones and of 2-(tetrazol-5-yl)alkanoic acid derivatives with lead tetraacetate. A novel method of preparation of alk-2-ynyl ketones and alk-2-ynoic acid derivatives

The majority of tetrazolylacetyl derivatives 2 and 7, when treated with lead tetraacetate in dry 1,4-dioxane at room or lower temperature, are oxidized with elimination of molecular nitrogen mainly to the corresponding alkynoyl derivatives 4 and 8, respectively. Vinylidenes (25) have been shown to be the intermediates of the reaction. The reaction does not take place when either the tetrazolyl group is N-substituted or the carbon atom separating the tetrazolyl and the carbonyl groups is disubstituted or these two groups are separated by two carbon atoms as in compound 17. The reaction offers a convenient method for the conversion of 2-cyanoacetyl derivatives into alk-2-ynoyl derivatives via intermediate tetrazolylacetyl derivatives. The 4-methoxyanilide 7o reacts differently, affording the fused heterocyclic compounds 19o and 20o.