10-Alkenylphenothiazines. 1. Synthesis and cis,trans-isomerization of 10-propenylphenothiazines

Monomeric and Polymeric Phenothiazine Photosensitizers for Photoinitiated Cationic Polymerization

“…Recrystallization of the resulting solid from ethanol gave 1.9 g (79%) PPT as graywhite needles with a mp of 32-35 °C (lit. 19 mp 34-35 °C). 1 H NMR spectroscopy indicated that the mixture contained 95% pure cis isomer.…”

“…The above method is considerably better than the previous synthesis reported for this compound involving a transvinylation reaction. 19 Monomer VPT was successfully polymerized (eq 8) using boron trifluoride etherate as a catalyst. The polymer, PVPT, was obtained as a colorless amorphous solid on precipitation in methanol.…”

Heterocyclization of N-propenyl-substituted phenothiazines and phenoxazines using electrophiles in an anhydrous medium

“…Column chromatography of the filtrate on silica gel also gave a 13.5% yield of the 1-ethyl-2-methyl-1H-pyrido[3,2,1-k,l]phenoxazine (6). It is likely that, along with the oligomerization of monomer 2 similarly to compound 1, there occurs an intramolecular alkylation of the dimer cation B2 arising to give the intermediate 1-ethyl-2-methyl-3-(phenoxazin-10-yl)-2,3-dihydro-1H-pyrido[3,2,1-k,l]phenoxazine (5).…”

“…We have previously reported the prototropic isomerization of N-allyl derivatives of phenothiazine and phenoxazine to give cis-10-propenylphenothiazine (1) [6] and cis-10-propenylphenoxazine (2) [7]. In the case of the acid hydrolysis of these compounds it has been shown [8] that they demonstrate an increased activity with relation to electrophilic reagents while the initial position of attack of a proton to form the carbenium-immonium intermediate of type A is the α-carbon atom of the substituent (Scheme 1 Stabilization of ion A is achieved by conjugation of the vacant p-orbital with the unshared electron pair of the nitrogen atom, the stabilization being more efficient for ion A1 than for ion A2 [9].…”

“…Calculated, %: C 75.28; H 5.47; N 5.85; S 13.40.1-Ethyl-2-methyl-1H-pyrido[3,2,1-k,l]phenothiazine (4).After distillation of the solvent from the filtrate from the synthesis of compound 3 the residue was loaded onto an L 100/160 silica gel column (70×2 cm) and eluted with a mixture of hexane and ether (2:1) to give compound 4 (0.63 g, 9%) with mp 69-70ºC (hexane). 1 H NMR spectrum (acetone-d6 ), δ, ppm (J, Hz): 0.96 (3H, t, J = 8, CH 3 CH 2 ); 1.60 (2H, m, CH 3 CH 2 ); 2.04 (3H, s, CH 3 ); 4.54 (1H, dd, J = 5, J = 3, H-1); 6.20 (1H, s, H-3); 6.60-6.70 (7H, m, H arom ). 13 C NMR spectrum (acetone-d 6 ), δ, ppm: 10.06 (C-1"); 21.12 (C-1'); 26.76 (C-2'); 60.39 (C-1); 114.33 (C-11); 120.25 (C-3); 125.25 (C-3'); 136.17 (C-2).…”