中文名称 | 英文名称 | CAS号 | 化学式 | 分子量 |
---|---|---|---|---|
—— | 2-(1',2'-dihydroxypropyl)-1,4-dimethoxy-3-(2''-methylprop-2''-enyl)anthraquinone | 254896-08-7 | C23H24O6 | 396.44 |
—— | 2-formyl-1,4-dimethoxy-3-(2'-methylprop-2'-enyl)anthraquinone | 254896-09-8 | C21H18O5 | 350.371 |
—— | (E)-1,4-dimethoxy-2-(2'-methylprop-2'-enyl)-3-(prop-1''-enyl)anthraquinone | 157197-03-0 | C23H22O4 | 362.425 |
—— | (E)-1-hydroxy-4-methoxy-2-(2'-methylprop-2'-enyl)-3-(prop-1''-enyl)anthraquinone | 254896-07-6 | C22H20O4 | 348.398 |
—— | 4-hydroxy-1-methoxy-2-(prop-1'-enyl)anthraquinone | 126308-21-2 | C18H14O4 | 294.307 |
—— | (E)-1-methoxy-4-(2''-methylprop-2''-enyloxy)-2-(prop-1'-enyl)anthraquinone | 254896-06-5 | C22H20O4 | 348.398 |
中文名称 | 英文名称 | CAS号 | 化学式 | 分子量 |
---|---|---|---|---|
—— | (7S,9S)-7,9-dihydroxy-9-hydroxymethyl-6,11-dimethoxy-7,8,9,10-tetrahydronaphthacene-5,12-dione | 254896-33-8 | C21H20O7 | 384.386 |
Tin(IV) chloride and titanium(IV) chloride mediated cyclizations of the ortho-allyl-substituted homochiral hydroxyanthraquinone acetals (7)-(10), prepared by optimized redictive Claisen rearrangements, have afforded monochloro and dichloro tetracyclic products, the tereochemistry of which has been assigned by using n.m.r. techniques. An Sn2-like process in which the dioxolan ring is maintained as an ion pair intermediate is favoured when either tin(IV) chloride or titanium(IV) chloride is used at -78�. Thereafter the direction of addition of chloride at C9 is largely governed by the orientation of this ion pair. An alternative path which probably involves a free oxocarbenium ion predominates at higher temperatures. An adjacent methoxy group on the anthraquinone lowers the stereoselectivity at both C7 and C9, possibly by bidentate coordination of the Lewis acid involving the quinone carbonyl, the methoxy oxygen and the acetal oxygens.
The methylidene tetracycle (2) has been synthesized in 11 steps from quinizarin (5) in an overall yield of 38% by using a highly ecient selective dihydroxylation step and an intramolecular ene cyclization. Also prepared with the selective dihydroxylation methodology were the silyloxy alkene (3) and the 6-demethoxy alkene (4). A mixture (1 : 2) of the (E)- and (Z)-isomers of the ethylidene compound (6) has been prepared by similar methods. The products resulting from the reactions of AD-mix-α and AD-mix-β on the alkenes (1)–(3) and (6) have been investigated and their stereochemistries assigned by using 1 H n.m.r. and NOESY experiments, and molecular modelling of acetonide derivatives. An X-ray crystal structure of the acetate (64) has confirmed the relative stereochemical assignments.