53(P1-1) 4-イリデンブテノライド系カロテノイドペリジニン及びピロキサンチンの全合成(ポスター発表の部)

抄録

Peridinin (1) and pyrrhoxanthin (3) are unique C_<37>-skeletal nor-carotenoids owing to the presence of a 4-ylidenebutenolide system carrying an allene or an acetylene function in the main polyene chain. Both pigments were found from the planktonic algae, dinoflagellates causing "red tide". Main pigment peridinin is known as an auxiliary light harvesting pigment for photosynthesis. Toward a total synthesis of these carotenoids, a novel synthetic method of carotenoidal ylidenebutenolides was developed via a reaction of the conjugated formyl ester (8) with the various allylic sulfones in the presence of LDA at ?78℃ (route C). In this reaction, addition, cyclization, and elimination took place successively in one pot to give expected products in moderate yields. By using this method, the first synthesis of peridinin (1) and pyrrhoxanthin (3) was achieved by the reaction of the C_<15>-epoxy formyl ester (35) with the conjugated C_<22>-allenic sulfone (23) or C_<22>-acetylenic sulfone (41). The formyl ester (35) was synthesized through 12 steps starting from (30) as shown in Scheme 6 which included the palladium catalyzed olefination of the enol triflate, the preparation of the allylic sulfone catalyzed by palladium (0) complex, and functionalization of the allylic sulfone. On the other hand, the sulfones (23) and (41) were prepared in 3 steps from the known allenic (21) and (22) or acetylenic (38) and (39) apo-carotenals, respectively. The condensation reaction between the formyl ester (35) and the sulfone (23) or (41) produced peridinin (1) or pyrrhoxanthin (3) accompanying its 11'E-isomer (36) or (43). Spectral properties of the synthetic (1) and (3) were good agreement with those of the respective specimens.