title: A chain extension method for apocarotenoids; lycopene and lycophyll syntheses.
abstract: The novel C5 benzothiazolyl (BT) sulfone containing an acetal group was prepared as a building block for the chain-extension of apocarotenoids. The double Julia-Kocienski olefination of the BT-sulfone with C10 2,7-dimethyl-2,4,6-octatrienedial and deprotection of the resulting acetal groups efficiently produced C20 crocetin dial. The higher homologues of C30 and C40 apocarotenoids were prepared from C20 crocetin dial by the repeated application of the Julia-Kocienski olefination of the C5 BT-sulfone and hydrolysis. The scopes of the Julia-Kocienski olefination in the total synthesis of carotenoid natural products were evaluated using the C10+C20+C10 coupling protocol. The olefination was sensitive to the steric factor and bulky C10 β-cyclogeranyl BT-sulfone was not able to react with C20 crocetin dial, however, lycopene and lycophyll were efficiently produced by the Julia-Kocienski olefination of C10 geranyl BT-sulfone and hydroxygeranyl BT-sulfone, in which protection of the hydroxyl group was not necessary.
authors.affiliation: Department of Energy and Biotechnology, Myong Ji University, Myongji-Ro 116, Cheoin-Gu, Yongin, Gyeonggi-Do 449-728, Republic of Korea.
authors.forename: Jeongae
authors.initials: J
authors.lastname: Choi
authors.affiliation: Department of Nano Science and Engineering, Myong Ji University, Myongji-Ro 116, Cheoin-Gu, Yongin, Gyeonggi-Do 449-728, Republic of Korea.
authors.forename: Eun-Taek
authors.initials: ET
authors.lastname: Oh
authors.affiliation: Department of Energy and Biotechnology, Myong Ji University, Myongji-Ro 116, Cheoin-Gu, Yongin, Gyeonggi-Do 449-728, Republic of Korea; Department of Nano Science and Engineering, Myong Ji University, Myongji-Ro 116, Cheoin-Gu, Yongin, Gyeonggi-Do 449-728, Republic of Korea; Department of Chemistry, Myong Ji University, Myongji-Ro 116, Cheoin-Gu, Yongin, Gyeonggi-Do 449-728, Republic of Korea. Electronic address: sangkoo@mju.ac.kr.
authors.forename: Sangho
authors.initials: S
authors.lastname: Koo
mesh_terms: D002338:Carotenoids / Q000138:chemical synthesis* / Q000737:chemistry; D060326:Chemistry Techniques, Synthetic; D000077276:Lycopene; D013450:Sulfones / Q000737:chemistry
chemical_list: D013450:Sulfones; D002338:Carotenoids; C514774:lycophyll; D000077276:Lycopene
keywords: Apocarotenoids; Carotenoids; Julia–Kocienski olefination; Lycopene; Lycophyll; Sulfone