Synthesis of Bixin and Three Minor Carotenoids from Annatto (Bixa orellana)
摘要:
The three apocarotenoids methyl (9Z)-8'-oxo-6,8'-diapocaroten-6-oate (2), methyl (9Z)-10'-oxo-6,10'diapocaroten-6-oate (4). and methyl (9Z)-14'-oxo-6,14'-diapocaroten-6-oate (5), recently isolated from annatto, were synthesized. The key step of all three syntheses was the Wittig reaction of the (Z)-terminus 6 with the phosphonium salts 15, 18, and 24, carrying the polyene chain. Bixin (1) was synthesized from 2 in a Horner-Emmons reaction.
Diphenylprolinol Silyl Ether Catalyzed Asymmetric Michael Reaction of Nitroalkanes and β,β-Disubstituted α,β-Unsaturated Aldehydes for the Construction of All-Carbon Quaternary Stereogenic Centers
作者:Yujiro Hayashi、Yuya Kawamoto、Masaki Honda、Daichi Okamura、Shigenobu Umemiya、Yuka Noguchi、Takasuke Mukaiyama、Itaru Sato
DOI:10.1002/chem.201403588
日期:2014.9.15
synthetic equivalent of the asymmetric Michael reaction of ethyl and acetyl substituents by means of radical denitration and Nef reaction, respectively. The short asymmetricsynthesis of (S)‐ethosuximide with a quaternary carbon center was accomplished by using the present asymmetric Michael reaction as the key step. The reaction mechanism that involves the E/Z isomerization of α,β‐unsaturated aldehydes
Asymmetric Diels-Alder Reaction of α-Substituted and β,β-Disubstituted α,β-Enals via Diarylprolinol Silyl Ether for the Construction of All-Carbon Quaternary Stereocenters
作者:Yujiro Hayashi、Bojan P. Bondzic、Tatsuya Yamazaki、Yogesh Gupta、Shin Ogasawara、Tohru Taniguchi、Kenji Monde
DOI:10.1002/chem.201602345
日期:2016.10.24
Diels–Alder reaction of α‐substituted acrolein proceeds in the presence of the trifluoroacetic acid salt of trifluoromethyl‐substituted diarylprolinol silylether to afford the exo‐isomer with both excellent diastereoselectivity and high enantioselectivity. In the Diels–Alder reaction of a β,β‐disubstituted α,β‐unsaturated aldehyde, good exo‐selectivity and excellent enantioselectivity was obtained when the
Verfahren zur Herstellung von 3-Alkoxycarbonylpropenalen und 3-Dialkoxymethylpropenalen
申请人:BASF Aktiengesellschaft
公开号:EP0502374A1
公开(公告)日:1992-09-09
Herstellung von 3-Alkoxycarbonylpropenalen und 3-Dialkoxymethylpropenalen der allgemeinen Formel Ia bzw. Ib
(R¹ = C₁-C₃-Alkyl; R² und R³ = H, Me oder Et; R⁴ und R⁵ = C₁-C₄-Alkyl, die zu einem 5- oder 6-gliedrigen Ring verbunden sein können) indem man einen entsprechenden Alkohol IIa oder IIb
mit Sauerstoff oder einem sauerstoffhaltigen Gas in der Gasphase in Gegenwart eines Metalls der Gruppe IB des Periodensystems oder einer Verbindung eines dieser Metalle als Katalysatoren umsetzt.
Die Verfahrensprodukte dienen als Zwischenprodukte für die Synthese von Carotinoiden.