Dahlbom, Richard published the artcileN- Alkyl – 3 – piperidyl phenothiazine – 10 – carboxylates, Category: piperidines, the publication is Acta Chemica Scandinavica (1961), 2043-6, database is CAplus.
cf. Biel, et al., CA 48, 694a; Schmitt, et al., CA 52, 1172d. From phenothiazine-10-carbonyl chlorides were prepared the title compounds, potential spasmolytic agents. 2-Methylphenothiazine (42.4 g.) in 750 ml. PhMe with 330 ml. 10% by volume COCl2-PhMe was refluxed 4 hrs. at 90°, 50 ml. EtOH added to the cold product, and the solvent evaporated in vacuo to give 54 g. 2-methylphenothiazine-10-carbonyl chloride, m. 122-2.5° (AcOEt). 2-Ethyl- (I) and 2-methoxyphenothiazine-10-carbonyl chloride (II) were similarly prepared I did not crystallize. II (88% yield) m. 94-5° (MeOH). In the modified method for the preparation of 2-chlorophenothiazine-10-carbonyl chloride (III) from 46.5 g. 2-chlorophenothiazine (IV), heating 6 hrs. at 140° was followed by addition of 130 ml. more COCl2 solution and heating 8 hrs. at 140°. Filtration, after the addition of C6H6 to the crude III, removed IV as a residue. Evaporation of C6H6 gave 35.0 g. III, m. 100-1° (AcOEt). AlCl3 (200 g.) was added to 131 g. phenothiazine-10-carbonyl chloride (V) stirred in 800 ml. CS2, the mixture refluxed to dissolve V, and to the cold product added 54.9 g. AcCl in portions. Heating to 30° started a vigorous reaction and after 1 hr. the mixture was refluxed 3 hrs. The cold lower layer from the product was poured on 1 kg. ice and 25 ml. 10N HCl to precipitate 150 g. 2-acetyl derivative of V, m. 120-2° (AcOEt), giving with KOH in EtOH 2-acetylphenothiazine. The appropriate 2-substituted V (0.05 mole), 0.05 mole N-methyl- (VI) or N-ethyl3-hydroxypiperidine (VII), 0.075 mole NEt3, and 50 ml. PhMe were refluxed (4 hrs. with VI, 8 hrs. with VII), the Et3NHCl filtered off from the cold product, the PhMe solution washed (H2O), and then extracted (N HCl). VIII.HCl separated, was dissolved in H2O, and the solution combined with the aqueous acidic extract before being made alk. (Na2CO3) to precipitate VIII. VIII was converted into VIII.HCl by HCl in Et2O or was quaternized (CA 49, 4659c). Thus, the following VIII and derivatives were prepared [R, R’, nature of derivative, recrystallizing solvent, % yield, and m.p. (the salts decomposed) given]: H, Me, free base, petr. ether, 72, 88-90°; H, Me, HCl, MeOH-Et2O (IX), -, 230-2°; H, Me, MeBr, MeOH, 86, 273-4°; H, Et, HCl, EtOH-Et2O (X), 55, 222-3°; H, Et. MeBr, X, 67, 232-3°; H, Et, EtI, X, 71, 220-1°; Me, Me, HCl, X, 92, 242-4°; Me, Et, HCl, X, 69, 223.-4°; Et, Me, HCl, MeOH, 80, 240-2°; Et, Et, HCl, X, 57, 202-3°; MeO, Me, HCl, IX, 80, 242-4°; MeO, Et, HCl, IX, 66, 230-1°; Cl, Me, HCl, IX, 77, 235-7°; Cl, Et, HCl, X, 64, 220-2°; Ac, Me, free base, EtOH, 80, 112-14°; Ac, Me, HCl, EtOH, -, 236-8°; Ac, Et, HCl, X, 49, 188-9°.
Acta Chemica Scandinavica published new progress about 13444-24-1. 13444-24-1 belongs to piperidines, auxiliary class Piperidine,Alcohol, name is 1-Ethylpiperidin-3-ol, and the molecular formula is C7H15NO, Category: piperidines.
Referemce:
https://en.wikipedia.org/wiki/Piperidine,
Piperidine | C5H11N – PubChem