“…Alkyne 9 was quantitatively hydrogenated to give Zselective alkene 10 by Lindlar catalyst with a drop of quinoline. Finally, removal of methyl groups of 10 gave desired bilobol 1 in 93% yield using methylmagnesium iodide at 1708C [22]. Synthetic 1 was identical in all respects ( 1 H, 13 C NMR, MS) with authentic data [3].…”
Concise total synthesis of bilobol 5-pentadecenylresorcinol (1), isolated from Gingko biloba fruits, has been achieved in 10 steps with 51% overall yield from 3,5-dihydroxybenzoic acid (3). Adipostatin A (2), isolated from the fruits as well as from Streptomyces cyaneus 2299-SV1, has also been synthesized in two steps from methylated bilobol (10). The structure-activity relationship study of synthetic products was described by means of cytotoxic assay against human KB carcinoma cell lines.
“…Alkyne 9 was quantitatively hydrogenated to give Zselective alkene 10 by Lindlar catalyst with a drop of quinoline. Finally, removal of methyl groups of 10 gave desired bilobol 1 in 93% yield using methylmagnesium iodide at 1708C [22]. Synthetic 1 was identical in all respects ( 1 H, 13 C NMR, MS) with authentic data [3].…”
Concise total synthesis of bilobol 5-pentadecenylresorcinol (1), isolated from Gingko biloba fruits, has been achieved in 10 steps with 51% overall yield from 3,5-dihydroxybenzoic acid (3). Adipostatin A (2), isolated from the fruits as well as from Streptomyces cyaneus 2299-SV1, has also been synthesized in two steps from methylated bilobol (10). The structure-activity relationship study of synthetic products was described by means of cytotoxic assay against human KB carcinoma cell lines.
“…Resveratrol and piceatannol were prepared starting from the same common material 3 using 4-methoxybenzaldehyde and 3,4-dimethoxybenzaldehyde, respectively, as electrophiles during the lithiation/condensation step at 0 °C, so the expected compounds 4e and 4f were isolated in moderate yield, after hydrolysis. These alcohols were dehydrated under DMSO reflux, giving the corresponding trans -olefins 8e and 8f , respectively, which after final full demethylation with an excess of methylmagnesium iodide (1:20 molar ratio) under heating at 100−160 °C gave resveratrol ( 9e ) and piceatannol ( 9f ) (Scheme ). 3 …”
The reaction of 3,5-dimethoxybenzyl trimethylsilyl ether (3) with different aldehydes (n-PrCHO, n-C(11)H(23)CHO, MeCHO, PhCHO) in the presence of lithium powder and a catalytic amount of naphthalene (4 mol %) gave, after hydrolysis, the expected alcohols 4 in moderate yields. The dehydroxylation of these compounds through the corresponding mesylates 5 or directly from benzylic derivatives by catalytic hydrogenation, afforded compounds 6, which are finally demethylated to yield 5-alkyl-3,5-dihydroxyresorcinols, such as olivetol (7a), grevillol (7b), 1,3-dihydroxy-5-propylbenzene (7c), or dihydropinosilvine (7d). Dehydration of alcohol derivatives 4 followed by demethylation led to hydroxylated stilbene-type structures, such as pinosilvine (9d), resveratrol (9e), or piceatannol (9f), which in some cases can be hydrogenated to give saturated molecules such as combretastanin B-4 tetramethyl ether (6f) or chrysotobibenzyl (6g). Finally, when the naphthalene-catalyzed lithiation of compound 3 was performed in the presence of other electrophiles [Me(3)SiCl, t-BuCHO, CH(3)(CH(2))(4)CHO, 4-Me(3)SiOC(6)H(4)CHO, (CH(2))(5)CO, PhN=C=O, PhN=CHPh], the expected reaction products 12 were isolated, after hydrolysis.
“…The method was also applied to diethylstilbestrol dimethyl ether (199). An interesting observation due to Wilds and McCormack (553) was that pyridine hydrochloride at 210°C. converted hexestrol monomethyl ether monobenzoate into the monobenzoate.…”
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