- Convergent Synthesis of Menaquinone-7 (MK-7)
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A practical synthesis of menaquinone-7 (MK-7, Vitamin K2) in the all-trans form was designed. Stereoselective synthesis of MK-7 was achieved through a "1 + 6" convergent strategy by condensation of two building blocks, menadione monoprenyl derivative (fragment "1") with hexaprenyl bromide (fragment "6", 82%). Pd-catalyzed desulfonation with LiEt3BH (78%) was followed by oxidation of the hydroquinone moiety using ammonium cerium(IV) nitrate (72%). The major challenge in our methodology was the preparation of all-trans hexaprenyl bromide by coupling of two triprenyl units derived from trans, trans-farnesol. Manufacturing on a pilot scale was accomplished through our approach. The scalable method was designed especially for a large, kilogram-scale production from easily available intermediates. Furthermore, the proposed methodology avoids many chromatographic purifications and allows for a relatively cost-effective manufacturing. Moreover, our synthesis yielded high-purity (99.9%) final product MK-7, which can be used as a dietary supplement as well as an active pharmaceutical ingredient.
- Baj, Aneta,Wa?ejko, Piotr,Kutner, Andrzej,Kaczmarek, ?ukasz,Morzycki, Jacek W.,Witkowski, Stanis?aw
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p. 1026 - 1033
(2016/11/11)
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- Convergent synthesis of menaquinone-7 (MK-7)
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A practical synthesis of menaquinone-7 (MK-7, vitamin K2) in the all-Trans form was designed. Stereoselective synthesis of MK-7 was achieved through a "1 + 6" convergent strategy by condensation of two building blocks, menadione monoprenyl derivative (fragment "1") with hexaprenyl bromide (fragment "6", 82%). Pd-catalyzed desulfonation with LiEt3BH (78%) was followed by oxidation of the hydroquinone moiety using ammonium cerium(IV) nitrate (72%). The major challenge in our methodology was the preparation of all-Trans hexaprenyl bromide by coupling of two triprenyl units derived from trans,trans-farnesol. Manufacturing on a pilot scale was accomplished through our approach. The scalable method was designed especially for a large, kilogram-scale production from easily available intermediates. Furthermore, the proposed methodology avoids many chromatographic purifications and allows for a relatively cost-effective manufacturing. Moreover, our synthesis yielded high-purity (99.9%) final product MK-7, which can be used as a dietary supplement as well as an active pharmaceutical ingredient.
- Baj, Aneta,Wa?ejko, Piotr,Kutner, Andrzej,Kaczmarek, L?ukasz,Morzycki, Jacek W,Witkowski, Stanisl?aw
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p. 1026 - 1033
(2017/01/16)
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- PROCESS FOR PREPARATION OF MK-7 TYPE OF VITAMIN K2
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Process for preparation of MK-7 type of vitamin K2 is characterized by attaching hexaprenyl chain of ?all-trans" configuration to monoprenyl derivative of menadiol following ?1 + 6" synthetic strategy. According to the invention, a-sulfonyl carbanion generated in situ from the protected monoprenyl menadiol of the formula (II), wherein R1 represents C1-3-alkyl group, is reacted with hexaprenyl halide of the formula (VII), wherein X represents halogen atom, preferably bromine, both Z' and Z' represent H or one of Z' and Z" represents H and the other represents phenylsulfonyl group -SO2Ph in the alkylation reaction. The hexaprenyl halide of formula (VII) is obtained by coupling two triprenyl units in alkylation reaction, with or without separation of the intermediates.
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