Marco contextual

diluted with water (250 ml.)» The resulting bright yellow suspension was extracted with methylene chloride

(200 + 50 ml.). The combined extracts wore dried (K_COg) and the volume of the orange solution reduced under water pump vacuum to ca. 50 ml. when acetonitrile (15 ml.) was added. The remaining methylene chloride was removed at atmospheric pressure. 6'~Formyl-6H-indeno[ 1 ,2-d] pyrido - [2,1-b] thiazolium anhydro-salt (32a) crystallised as orange plates (212 mg., 60%). A sample recrystallised

% from nitromethane melted at 213-220 (decomp.)(Pound:

0,71.7; H,3.8. requires 0,70.4; H,3.3%). I

Perchloric acid (0.1 ml.) was added to a warm ,1 solution of the aldehyde (0,125 g., 0.5 m.moles) in

nitromethane (5 ml.). The pale yellow needles which j ■y separated immediately wore filtered off and washed with

ether to give 6-hydroxymethylene-indeno[ 1,2-d] pyrido - ^ [2,1-b] thiasoliun perchlorate (33a) (0.135 g ., 94%). I

A sample recrystallised from acetonitrile decomposed slowly >200^. (Pound: H,2,0; N,4.3.

C.yI-L _ClNO^S requires C,51.2; H,2.0; N,4.0%)._{i o Jl 'O o}

(ii) The 6-acetyl derivative. Triethylamine (5,56 ml., 40 m.moles) was added all at once to a solution of the

salt (lS)(0.ô48 g., 2 m.moles) and acetic anhydride (3.70 ml., 40 m.moles) in acetonitrile (30 ml,). An immediate deep

red colouration was produced. The mixture was boiled for 2 min. during which time the solution became orange-red and was then poured into water to give a yellow suspension. This was left overnight and extracted with methylene chloride. The dried extracts (Na^SO^) were evaporated and the residue, dissolved in methylene chloride (150 ml,), chromatographed on a column of alumina (2.C x 25 cm.) prepared with

methylene chloride* The solvent was changed gradually to pure acetonitrile during which process two fractions

(both ca, 250 ml.) - one purple, the other blue - were

collected. Neither contained useful material. The solvent _Yi? was now changed to a 3% solution of methanol in acetonitrile ^ ana a yellow fraction (700 ml.) was eluted. The residue

obtained from this fraction was rechromatographed on the same sise of alumina column prepared with acetonitrile* A small amount of purple-blue material (which was ignored) was eluted with acetonitrile (200 ml.}. The solvent was

104.

then changed gradually to 3% methanol in acetonitrile when a yellow band was eluted (SCO ml.). Evaporation yielded a residue, recrystallised from methanol (15 ml.) by

displacement of methylene chloride to give 6-ocetyl-6H- indeno[1,2-d] pyrido[2,1-b]thiazolium anhydro-salt (32b) (256 mg.) as golden yellow plates. The mother liquors, after rechromatography, yielded a further crop (110 mg.)

(iii) The 6-methoxycarbonyl derivative. Triethylamina

bringing the total yield to 366 mg. (69%). A sample | recrystallised for analysis from nitromethane at 244-248^

(Found: c,71.5;H,4.0. requires 0,72.4; h ,4.2%).

Perchloric acid (0.2 ml.) was added to a hot suspension of the ketone (0.265 g., 1 m.mole) in ethanol (30 ml.).

ri The ketone dissolved and a pale yellow crystalline 8

precipitate separated on cooling. This was filtered off

and washed with ether to give 6-(1~hydroxyethylidene)indeno - | [ 1,2-d] pyrido[2,1-b] thiazolium perchlorate (33b) (0.346 g ., |

I

95%) as pale yellow needles. A sample recrystallised from 'y 4

O ":4

acetic acid decomposed y 230 (Found: 0,52.3; H,3.2. C^^H^gCINOdS requires 0,52.5; H,3.3%).

(5.56 ml., 40 m.moles) was added all at cnee to a solution

of the salt (0.648 g., 2 m.moles) in acetonitrile (50 ml.) j and then methylchloroformate (3.12 ml,, 40 m.moles) was

105

added dropwise to the resulting deep purple solution during ^ 20 sec., during which time the colour of the solution

changed to brown-red and effervescence took place. The

solution was then boiled for 2 min. before being poured ÿ % into water. The resulting yellow suspension was extracted

with methylene chloride (4 x 100 ml.). The combined

extracts were dried (Na SO ) and removal of solvent gave a_{2 4} dark brown solid residue which was chromatographed on a column of alumina (2.8 x 30 cm-), prepared with methylene chloride.

After all the material had been placed on the column with methylene chloride the solvent was changed gradually (in 300 ml. of solvent) to 25% acetonitrile in methylene chloride when a small amount of violet material was eluted.

(This material v/as ignored). Increasing the concentration of the acetonitrile to 40% caused elution of an orange

band in 250 ml. of solution. 1

J

Removal of solvent yielded a crystalline residue which was recrystallised from methanol (10 ml.) by displacement of methylene chloride to give 8-methoxycarho:iy].-JIZ-indeno- [1,2-d] pyrido[ 2,1-b] thiazolium anhydro-salt (32c) (0.463 g.,

82%) as golden yellow needles. A sample recrystallisod from 4 ethanol melted at 200-205° (Found; 0,60.3; H, 4.00.

106,

Perchloric acid (0.1 ml.) was added to a cold suspension

I

of the _{ester (0.141 g., O,5 m.mole) in acetonitrile (5 ml,).}

Colourless crystals slowly separated from the resulting solution. Bther (10 mlc) was added to complete the precipitation. The product was filtered off and washed with ether to give 6-methoxycarfoonyl-6H~indeno[ 1,2-d] pyrido

[2,1 -h] thiazoliuni perchlorate (34 ) (0.173 g ., 91 %) as colourless granular prisms. (Found; 0,50.5; H,3«4. requires 0,50.3; H,3.2%).

(iv) The 6-(1,2-dimethoxycarbonylyanyl) derivative, g .11 Triethylamine (0.28 ml., 2 m.moles) was added to a solution

of the salt (19)(0.324 g., 1 m.mole) and dimethylacetylene - dicarfooxylate (0.246 ml. , 2 m.moles) in acetonitrile (10 ml.). Almost immediately a crystalline precipitate separated. This was filtered off after 4 hr. to give S-(1,2-dimetI-ozycarbonyl - viny1)-6H-indeno[ 1,2-d] pyrido[ 2,1-b] thinso1ium anhydro-saIt

(32d)(0.2S2 g«, 77%), A sample recrystallised from

acetonitrile as red needles m.p. 225-228°(Found; CyG5*7; H,4«3o C T-Î. _{20 15 4} requires C,65.^; H,4.1%)#

Perchloric acid (0,05 ml.) was added to a suspension of tne diester (0*092 g., 0.25 m.mole) in acetonitrile. Addition of other (2 ml.) caused yellow prisms to separate. These were filtered off and washed with other to give

G-(1,2-dimethoxycarbonylothylidene)-indeno[1,2-d] pyrido - [2,1-b] thiazolixnn perchlorate (35)(0.115 g., 99%). A sample

250-261 °(decomp. XFotind; C,52.1; H,3.6- C_ Ji. ^ClHO S_{20 i Ü o} requires C,51.6; H,3.6%).

XI; Preparation of Derivatives of the Indono[l,2,3-hc]-1- thiacyclL2,3,3] azine System.

(i) 9,1 Q-Dimetlioxycarbonylisideno[ 1,2,3-b,cj-1 thiacyGlo[2,3,3] asine. A solution of the diester(2Sf)

(0.365 g., 1 m.mole) in nitrobenzene (10 ml.) was boiled under refltus for 3 min. Solvent was removed from the dark brown solution and the residue chromatographed on a column of alumina (2.8 x 28 cm.) prepared with methylene chloride. A purple band was eluted first but lemoval of solvent gave

no useful product. A green band was then eluted (400 ml.). No other material was eluted with methylene chloride. The residue after removal of solvent from the green solution was recrystallised from acetonitrile by displacement of methylene chloride to give 9,lO-dimethoxycarbonylindeno-