Preparation of 3,4-dihydro-2H-1,3-benzoxazines

N,N-Di(butoxymethyl)alkylamines react with phenols under mild conditions to yield substituted 3,4-dihydro-2H-l,3-benzoxazines.     

Synthesis of 3-Phenyl-6-formyl-3, 4-dihydro-2H-1, 3-benzoxazine

Benzoxazine is a novel class of thermosetting resins, which possesses lots of outstanding properties such as no by-products and near-zero shrinkage during polymerization as well as good molecular design flexibility1-2. Furthermore, polybenzoxazines (PBZs)…     

Preparation of fused 1,3-oxazine-2,4-diones as potential antitumor agents

A series of indole, thiophene and pyrrole-fused 1,3-oxazine-2,4-diones, 2-methyl-1,3-oxazin-4-ones and 2-dimethylamino-1,3-oxazin-4-ones were synthesized and evaluated as antitumor agents.     

Pyrimidine derivatives and related compounds. 38. Synthesis of 1,3-oxazine-2,4-diones and their reaction with nucleophiles. Ring transformation of 1,3-oxazines to pyrimidines

5,6-Unsubstituted 1,3-oxazine-2,4-diones ( 3 ) and 6-unsubstituted 5-methyl-1,3-oxazine-2,4-diones ( 4 ) were prepared by reduction of the corresponding 6-chloro derivatives ( 1 and 2 ). Treatment of 6-chloro-3-methyl-1,3-oxazine-2,4-dione ( 1a ) with sodium azide, sodium cyanide, secondary amines and aniline gave the corresponding 6-substituted compounds ( 7, 9, 10 and 11 ) while the reaction of 1a and 2a,b with primary aliphatic amines such as methylamine and ethylamine caused a ring transformation to pyrimidine ring system giving barbituric acids ( 13a-d ).     

A convenient synthesis of 3,4-dihydro-2-methyl-3-oxo-2H-1,4-benzoxazine-2-carboxylic acids and 3,4-dihydro-2-methyl-3-oxo-2H-pyrido[3,2-b]-1, 4-oxazine-2-carboxylic acid

A convenient one pot synthesis of ethyl 3,4-dihydro-2-methyl-3-oxo-2H-1,4-benzoxazine-2-carboxylates and 3,4-dihydro-2-methyl-3-oxo-2H-pyrido[3,2-b]-1,4-oxazine-2-carboxylates and their conversion into the respective carboxylic acids are described.     

A novel dilithiation approach to 3,4-dihydro-2H-1,3-benzothiazines, 3,4-Dihydro-2H-1,3-benzoxazines,and 2,3,4,5-tetrahydro-1,3-benzothiazepines

3,4-Dihydro-2H-1,3-benzothiazines 4, 3,4-dihydro-2H-1,3-benzoxazines 9, and 2,3,4,5-tetrahydro-1,3-benzothiazepines 6 were synthesized by directed ortho-lithiation of thiophenols and phenols and by side-chain lithiation of substituted thiophenols, respectively, in one-pot by reacting with N,N-bis[(benzotriazol-1-yl)methyl]amines 3 as 1,3-biselectrophile synthons.     

Synthesis and alkylation of 3,4-dihydro-1H-1,3-4-benzotriazepine-2,5-diones and related systems

A synthesis of the 1,3,4-benzotriazepine-2,5-dione 2a and its 2-thio analog 11 is described. The key step was the mild and efficient cyclization of the o-(aminobenzoyl)hydrazine 10 , obtained from the reaction of a protected hydrazine derivative with the o-nitrobenzoyl chloride 3 . Alkylation of 2a takes place exclusively at N -3 while alkylation of 11 takes place on sulfur. Cyclization of the o-(aminobenzoyl)hydrazine 14 gave the 2,4(1H,3H)-quinazolinedione 15 as the sole product.     

3-Alkyl- bzw. 3-Aryl-3,4-dihydro-6-methyl-2(1H)-pyrimidinthione durchDimrothumlagerung von 2-Amino-4H-1,3-thiazinen

The 3,4-dihydro-3,4,4,6-tetramethyl- and 4,4,6-trimethyl-3-phenyl-2(1H)-pyrimidinethione (1 c, d), resp. as well as the corresponding trimethyl compound1 e are formed byDimroth rearrangement of 2-methylamino- and 2-amino-4,6,6-trimethyl-6H-1,3-thiazine (2 a, b) and of 3,6-dihydro-4,6,6-trimethyl-2-phenylimino-2H-1,3-thiazine (3 b), resp. The rearrangement takes place under thermal heterolysis of the 1–6 bond of2 a, b and3 b. The reactive behaviour1 c, d is almost equal to1 e, but the pyrimidine ring of1 d is more labile than those of1 c, e.     

Photophysical and Electrochemical Investigations on Photoconducting Poly(6-tert-butyl-3,4-dihydro-2H-1,3-benzoxazine)

Poly(6-tert-butyl-3,4-dihydro-2H-1,3-benzoxazine) was synthesized by thermally activated cationic ring opening polymerization. The structure of the polymer was confirmed by spectral and thermal studies. The highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) were estimated using cyclic voltammetry and optical absorption. Modulated photocurrent measurement technique was employed to study the spectral and field dependence of photocurrent. Photocurrent of the order of 1.5 µA/m² was obtained for polymer at a biasing electric field of 40 V/µm.     

Fragmentation of enamides derived from 6,7-dimethoxy-4-methyl-2H-1,3-benzothiazin and 3,4-dihydro-6,7-dimethoxy-1-methylixopuinoline

The electron impact mass spectra of several enamides have been examined. The enamides were prepared by reaction of aroyl halides with 6,7-dimethoxy-4-methyl-1,3-benzothiazin, and with 3,4-dihydro-6,7-dimethoxy-l-methylisoquinoline. The fragmentation pathways that have been proposed are supported by ion composition determinations and by mass-analysed ion kinetic energy spectrometry experiments carried out on the molecular ions and major fragment ions. The spectra are characterized by a loss of carbon monoxide from the molecular ion of each compound, a process which is accompanied by migration of the aryl group.     

3-芳胺甲叉-6-苯基-5,6-二氢-2H-吡喃-2,4-二酮类新化合物的设计与合成

交链孢酸;杀菌剂;双键顺反异构;3-芳胺甲叉-6-苯基-5;6-二氢-2H-吡喃-2;4-二酮类新化合物的设计与合成