S-Phenscylation of 6-Methyl-4-oxo-2-thio-2,3-dihydro-4H-1,3-oxazine and the Ring Transformation of the S-Phenacylated Compound

Sasaki, Tadashi; Ito, Eiji; Asai, Koji

doi:10.3987/r-1983-06-1089

Cited by 8 publications

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“…N-(chlorocarbonyl) isocyanate was reacted with diphenyl acetone (1) at 60-130°under nitrogen, to give 6-benzyl-5-phenyl-1,3-oxazine-2,4(3H)-dione (2) in 45% yield, using the method of Jaeger et al [5]. Compound 2 was reacted directly with allyl amine according to literature procedures [6,7] to give the N-1 alkylated pyrimidinedione-analogue 3 in 20% yield. The synthesis of the MKC-442 analogue containing the ethoxymethyl group at N-1 was not possible by this procedure because the ethoxymethyl amine is unstable and cannot be isolated.…”

Section: -[2-(hydroxyethoxy)methyl]-6-(phenylthio)thymine (Hept) Wasmentioning

confidence: 99%

Synthesis and anti‐HIV activity of HEPT and S‐DABO‐analogues with 5‐Benzyl and 5‐Phenyl substituents

Larsen

Aal

Pedersen

et al. 2001

Journal of Heterocyclic Chem

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6-Benzyl-5-phenyluracil (4) and 5,6-dibenzyluracil (9) were synthesised from diphenyl acetone (1) and ethyl 3-oxo-4-phenylbutyrate (6), respectively. The uracils were alkylated to afford the 1-alkoxymethyluracils 5, 10 and 11. Furthermore, S-alkylated dihydroalkoxybenzyloxopyrimidine (S-DABO) analogues were prepared by alkylating 5,6-dibenzyl-2-thiouracil (8) on sulfur to yield compounds 12a-f. All compounds were tested for their inhibition of HIV-1 reverse transcriptase, and moderate activity was found for 6-benzyl-1-(ethoxymethyl)-5-phenyluracil (5).

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Section: -[2-(hydroxyethoxy)methyl]-6-(phenylthio)thymine (Hept) Wasmentioning

confidence: 99%

Synthesis and anti‐HIV activity of HEPT and S‐DABO‐analogues with 5‐Benzyl and 5‐Phenyl substituents

Larsen

Aal

Pedersen

et al. 2001

Journal of Heterocyclic Chem

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“…In recent years we are interested in unsaturated 1,3-oxazines as starting materials for the preparation of various heterocyclic compounds: pyrimidines, 1Ð4 pyridines, 5,6 1,2oxazoles, 7 1,2-diazoles, 8 1.3-thiazoles, 9 1,2,4-triazoles, 8,10,11 and 1,2,4-oxadiazoles. 7 We previously optimized methods for the preparation of unsaturated 1,3-oxazin-6-ones and studied their reactions with electrophilic and nucleophilic reagents.…”

mentioning

confidence: 99%

Reactions of Unsaturated 1,3-Oxazines; I. Reaction of 6-Alkoxy-2-aryl-4H-1,3-oxazine-4-one with Hydrazine Derivatives

Prep'yalov¹,

Yakovlev²,

Zakhs³

1999

Synthesis

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6-Alkoxy-2-aryl-4 H -1,3-oxazin-4-ones 1aÐe react with hydrazine ( 2a ) and phenylhydrazine ( 2b ) with ring opening at the C-2-O followed by recyclization to 1,2,4-triazole-5-acetic acid esters 3aÐe . Reactions of the title compounds with unsymmetrical dimethylhydrazine 2c led to formation of 2-substituted 4-hydroxyimidazole-5-carboxylates 5aÐc.In recent years we are interested in unsaturated 1,3-oxazines as starting materials for the preparation of various heterocyclic compounds: pyrimidines, 1Ð4 pyridines, 5,6 1,2-oxazoles, 7 1,2-diazoles, 8 1.3-thiazoles, 9 1,2,4-triazoles, 8,10,11 and 1,2,4-oxadiazoles. 7 We previously optimized methods for the preparation of unsaturated 1,3-oxazin-6-ones and studied their reactions with electrophilic and nucleophilic reagents. 12Ð14 Now, we focus on ways of formation and properties of unsaturated 1,3-oxazin-4-ones. 15Ð17 The present communication reports on the reaction of 2-substituted 6-alkoxy-4 H -1,3-oxazin-4-ones with hydrazine derivatives. Our previous results on reactions of oxazines with ammonia and primary amines showed that the nucleophile attacks the C-2 atom with subsequent cleavage of the C-2-O bond and recyclization to 4,6-dioxopyrimidines, 16 which is generally consistent with published data on similar reactions. 1Ð4 Also, 2-substituted 6-methyl-4 H -1,3-oxazin-4-ones are known to react with hydrazine and phenylhydrazine to afford the corresponding 1,2,4-triazole derivatives. 8,10,11 Apart from hydrazine and phenylhydrazine, we also examined the reactions with N,N -dimethylhydrazine. The initial 2-substituted 6-alkoxy-4 H -1,3-oxazin-4-ones 1aÐe were synthesized from the corresponding aroyl isocyanates and alkoxyacetylenes (at a ratio of 1:1.15) using the procedure porposed by Chitwood et al. 18 The results of our quantum-chemical investigation of the reaction of aroyl isocyanates with methoxyacetylene were reported previously. 17 2-Substituted 6-alkoxy-4 H -1,3-oxazin-4-ones 1 aÐc react with hydrazine 2a and phenylhydrazine 2b to give triazoles 3aÐe in good yields. As expected, these products were formed as a result of primary attack by the amino group of hydrazine on C-2 with ring opening at the C-2-O bond. The subsequent recyclization involves the second nitrogen atom of the hydrazine and the carbonyl carbon atom in the open-chain intermediate; elimination of water molecule leads to triazoles 3aÐd in 60Ð90% yield (Table 1). Hydrazine ( 2a ) reacts with 1,3-oxazine 1a in ethanol at room temperature within 1 h to afford 90% of triazole 3a, whereas less nucleophilic phenylhydrazine ( 2b ) reacts with 1aÐc at a lower rate. Heating the reaction mixture under reflux for 7Ð8 h yields 52Ð73% of triazoles 3bÐd. A possible reaction mechanism is shown in Scheme 1. Hydrazines 2a,b attack the electrophilic center (C-2) of the oxazine ring; opening of the latter gives intermediates A and B . Intermediate B undergoes ring closure due to nucleophilic attack by the nitrogen atom on the carbonyl carbon atom; the resulting unstable heterocycles C and D Scheme 1 Downloaded ...

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ChemInform Abstract: S‐PHENACYLATION OF 6‐METHYL‐4‐OXO‐2‐THIO‐2,3‐DIHYDRO‐4H‐1,3‐OXAZINE AND THE RING TRANSFORMATION OF THE S‐PHENACYLATED COMPOUND

Sasaki¹,

Ito²,

Asai³

1983

Chemischer Informationsdienst

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S-Phenscylation of 6-Methyl-4-oxo-2-thio-2,3-dihydro-4H-1,3-oxazine and the Ring Transformation of the S-Phenacylated Compound

Cited by 8 publications

References 0 publications

Synthesis and anti‐HIV activity of HEPT and S‐DABO‐analogues with 5‐Benzyl and 5‐Phenyl substituents

Synthesis and anti‐HIV activity of HEPT and S‐DABO‐analogues with 5‐Benzyl and 5‐Phenyl substituents

Reactions of Unsaturated 1,3-Oxazines; I. Reaction of 6-Alkoxy-2-aryl-4H-1,3-oxazine-4-one with Hydrazine Derivatives

ChemInform Abstract: S‐PHENACYLATION OF 6‐METHYL‐4‐OXO‐2‐THIO‐2,3‐DIHYDRO‐4H‐1,3‐OXAZINE AND THE RING TRANSFORMATION OF THE S‐PHENACYLATED COMPOUND

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