Studies on Heterocyclic Colouring Matters Part II: Δ^2,2′ ‐Bi (2H‐1, 4‐benzothiazines)

Abstract

A novel one‐step ‘Inverse Indigo Synthesis’ of the Δ2,2′‐bi(3,4‐dihydro‐3‐oxo‐2H‐1, 4‐benzothiazine) chromophore is described. Structure, substitution reactions, mechanism of formation, colour and other relevant properties of this system have been investigated in relation to known thioindigos. A synthesis of the basic skeleton of one of the ‘Trichosiderins’, the colouring matters of human red hair, is reported.

Structure determination of 6,6′-bis(trifluoromethyl)-thiazine-indigo from laboratory powder data and lattice-energy minimisation

“…The refined structure shows that the yellow pigment 2 exhibits a dense and efficient packing (r ¼ 1.7875 g/cm 3 ). This explains the experimentally observed insolubility.…”

“…1) [3]. The resulting cis-isomer of (CF 3 ) 2 THI is subsequently heated to reflux in a mixture of N,N-dimethyl-formamide (DMF) and acetic acid for 3 hours; thereby the cis-isomer transforms to the trans-isomer, 2, in the a-phase.…”

Isomers and aza‐analogues of indoxyl containing nitrogen at a ring‐fusion position: Coupling reactions with electrophiles and attempted oxidations

“…Although spectral data ('H, nmr) confirmed the oxidation process [25], the elemental analysis of dimer l l b is not satisfactory. The uv-visible spectrum of l l b in acetic acid is recorded in Table 3.…”

“…Recrystallisation gave 54 as green cubes (from acetone), mp 240' dec; ir (nujol): 2500 br, 1580, 1540, 1163 3.38 (s, 6H, NMe,), 7.23 (5, lH, CH=C), 7.4-8.2 (m, 16H, Ar-H), "C nmr (deuteriochloroformltrifluoroacetic acid): 6.7 (q, CH,), 47.2 (q, NMe,), 109.6 (s, C-l), 150.0 (s, C-6), 154.9 (s, C-5), 156.3 (s, C-9), 156.4 (s, CS), 113.7 (d), 120.5 (d), 121.4 (d), 127.5 (d), 127.9 (d), 130.2 (d), 131. 4 (d), 132.2, 132.6, 133.0, 133.2, 133.4, 133.6, 134.5 (d), 135.5, 143.7; ms: miz 431 (20%), 430 (70), 429 (82), 428 (19), 413 (18), 311 (lo), 310 (33), 299 (25), 298 (1 7), 215 (18), 147 (1 l), 134 (70). 43 (19), 38 (30), 36 (loo), 28 (20)…”

Studies on Heterocyclic Colouring Matters Part III: 7a,14a‐diaza‐7,7a,14,14a‐tetrahydroquino[2,3‐b]acridine‐7,14‐diones (5,7a,12,14a‐tetraaza‐7,7a,14,14a‐tetrahydropentacene‐7,14‐diones)

“…-Diethyl 2,5-dioxo-cyclohexane-li4-dicarboxylate (diethyl succinylsuccinate) (l), when treated with aniline in aceticacid under refluxleads to I ) 2, Part I, [l]. Part 11, [2]. Presented at the 6th International Colour Symposium in Freudenstadt, Germany, September 27-October 1, 1976.…”