Ring-chain tautomerism in 1,3-oxazines

Abstract

of unlabeled 2. The quenching factor, 1.3027, was used to normalize the counts of samples of 2 from rearrangement.Calculations of HIE were made as described earlier.30 Irradiation of 4-Methoxyphenyl Acetate (1), 2-Acetyl-4methoxyphenol (2), and 4-Methoxyphenol for Spectroscopic Measurements. Solutions of these compounds were irradiated in the Rayonet reactor as described above. Samples (3 mL) were withdrawn at timed intervals for recording absorbance at 356 nm. Neither 1 nor 4-methoxyphenol absorb in this region. Data for irradiations of 1 in the absence and presence of propanethiol are given in Figure 1. They show the formation and slow decomposition of 2 in the absence of propanethiol and the formation and stability of 2 in its presence. Data for the prolonged irradiation of 2 alone and in the presence of propanethiol, 2,3-butanedione, and 4-methoxyphenol are given in Figure 2. Included in Figure 2 are data for the irradiation of 4-methoxyphenol alone. This compound was itself decomposed by prolonged irradiation at 300 nm, and the unknown product(s) of decomposition absorbed weakly at 356 nm.The following absorbance data (X^[nm], t) are pertinent: 1

The trans–cis and the azide–tetrazole ring-chain isomerization of 2-azido-1,3-azoles: Quantum chemical study

“…Therefore, ring-chain isomerism is an important aspect of organic chemistry [2][3][4][5][6][7][8][9][10][11][12][13][14].…”

Electron ionization mass spectra of some cyclohexane fused 2‐N‐phenyliminoperhydro‐1,3‐oxazines and related thiazines

“…, 68(19), 67(23), 57(15), 56(5), 55(14), 54(11), 53(5), 42(43),41(20) 262(6), 261(21), 260(M" ,100) 259(39), 227(13), 213(11), 170(7), 169(6), 167(10), 166(14), 165(9), 164(11), 156(9), 136(10), 135(11), 133(25), 132(59), 131(13), 114(8), 106(17), 104(11), 96(5), 95(29), 93(10), 92(5), 91(35), 81(6), 77(27), 70(7), 68(5), 67(10), 65(5), 61(29), 57(14), 55(8), 53(5), 51(7), 45(5), 42(21), 41(18) 262(6), 261(19), 260(M+ , loo), 259(37), 227(7), 213(12), 170(13), 166(6), 165(6), 164(10), 156(10), 136(7), 135(9), 133(17), 132(63), 131(12), 124(11), 106(14), 104(10), 95(11), 93(5), 92(5), 91(22), 81(6), 77(23), 68(5), 67(8), 61(29), 57(14), 55(9), 53(5), 51(6), 42(23), 41(16) Compound , 320(M+ ,42), 319(14), 246(9), 245(54), 228(7), 225(6), 224(12), 202(12), 182(8), 170(5), 158(7), 150(21), 133(7), 132(68), 119(10), 106(24), 104(7), 96(13), 95(12), 93(15), 92(10), 91(100), 81(18), 79(6), 77(8), 68(6), 67(13), 65(8), 55(7), 54(6), 41(9) 338(7), 337(22), 336(M+ ,92), 335(20), 303(7), 289(6), 245(7), 244(29), 242(6), 240(5), 239(6), 232(6), 209(6), 208(22), 207(46), 182(12), 167(7), 148(18), 137(13), 136(17), 135(6), 131(7), 106(13), 105(6), 104(11), 95(32), 93(10), 92(9), 91(100), 77(16), 67(7), 65(18), 55(8), 51(5), 41(14) Compound I2 338(7), 337(22), 336(M+ , loo), 335(31), 303(5), 289(7), 245(6), 244(26), 239(6), 232(7), 208(20), 207(45), 182(12), 170(12), 167(12), 148(16), 137(12), 136(16), 135(5), 131(6), 106(13), 104(10), 95(11), 93(7), 92(8), 91(92), 77(16), 67(7), 65(10), 41(10)…”

ChemInform Abstract: Fused‐Skeleton Saturated Six‐Membered 1,3‐N,O, N,N and N,S Heterocycles. Fused‐Skeleton Aryl‐Substituted Saturated Isoindolones

“…The crucial difference in the reactivities of the cis and trans-1 ,Zdisubstituted 1 ,Sdifunctional cyclopentane derivatives was used, for example, for the separation of the cis-and trans-2-hydroxymethylcyclopentanol isomers,(100) because the trans isomer did not undergo ring closure to frans-trimethylene-l,3dioxane. imidates, when the reaction product was the cistrimethylenepyrimidinone derivative (60). (28) After numerous unsuccessful trials, the first successful cyclizations of trans-1 ,Zdisubstituted 1,3-difunctional cyclopentane derivatives to cyclopentanetransfused six-membered 1,3-heterocycles were the reactions of trans-2-aminomethylcyclopentanol (61) and its N-Me derivative (62) to trans-5,6-trimethylene-1 ,3-oxazin-2-ones (63, 65) and trans-5,Strimethylene-1 ,3-oxazine-2-thiones (64,66).v3) This remarkable trans ring-closure reaction was reported more than 10 years ago.…”