Pyrrolylpolyenes. Part 6. Synthesis of wallemia A and wallemia E

Abstract

The pigments (4€,6€,8€, 1 O € ) -2,6-dimethyl-5hydroxy-1 1pyrrol-2-ylu ndeca -4,6,8,10-tetraen -3one (wallemia A) and (4€,6€,8€,1 0E)-I 1 -(3-chloropyrrol-2-yl)-2,6-dimethyl-5-hydroxyundeca-4,6,8,10-tetraen-3-one (wallemia E), identical with the compounds extracted from the fungus Wallemia sebi, have been synthesised. Analogous p-enamino ketones were by-products of the synthesis.In Part 5 we reported revised structures for the pyrrolylpolyene pigments isolated ' from the fungus WaZZemia sebi (Fr.) v. Arx.The syntheses of two of the principal pigments, wallemia A (7) and wallemia E (12), have now been carried out following routes established in our earlier syntheses of pyrrolylpolyene P-diketones.Reduction of pyrrolylpolyene esters such as (1) with lithium aluminium hydride yields the corresponding allylic alcohols, but these are highly unstable under the reaction condition^.'^^ Reduction of (1) using di-isobutylaluminium hydride, however, permitted the isolation of the alcohol (3) in reasonable yield.

Carotenoids and related compounds. Part 40. Synthesis of trikentriorhodin and other β-diketones

“…After 15 rnin the solution had h,,,, 452 and 426 nm. 496.334, 55), 478 ( M -18, l), 411 (6), 195 (71), 180 6,6'-Dihjdroxv-18,18'-dinor-3,3'-diupo-~,~-curotene-4,4'done (9).-Prepared from 8,8'-diapo-carotene-8,8'-dial and acetylacetone by the procedure described in the previous experiment, the bis-P-diketone (80%) had m.p. 225 "C (with decomp.…”