Synthèse de méthyl-3 furoquinones

Abstract

Les auteurs proposent deux nouvelles solutions a u problkme de la synthkse de methyl-3 furoquinones. Ces methodes ont I'avantage de requerir des substrats et des reactifs facilement accessibles. Une nouvelle synthkse de la tanchinone I(26) illustre I'un des procedes qui devraient en principe s'appliquer tgalement a la synthese d'isotanchinones. Au cours de cette etude, quelques transformations inedites ont aussi kt6 observees.The authors propose two new solutions to the problem of the synthesis of 3-methylfuranquinones. The methods have the advantage of requiring readily accessible substrates and reagents. A new synthesis of tanshinone I(26) illustrates one of the processes which in principle should also be applicable to the preparation of isotanshinones. Several novel transformations have been observed in the course of this study.Can. J. Chem., 52,88 (1974) Synthkses de furonaphtoquinones Les quinon-s cornportant un heterocycle oxygtnt ont souvent t t t isoltes de sources naturelles (1) et, puisque certaines proviennent probablernent des composts hydroxylts correspondants, nous avons recherche des rntthodes de synthtse B l'aide de ces intermtdiaires. Depuis le dtbut de ces travaux, un certain nombre de synthtses de mtthyl-3 furoquinones ont Ct C rtalistes (2-4). Nos rntthodes constituent toutefois des proctdts nouveaux et de plus cette ttude nous a perrnis d'observer des rtactions inidites concernant la formation d'alkyl-2 furoquinones.Le problkrne principal, celui de la prtparation de mtthyl-3 furoquinones, a ett abordi par 1'Ctude de la synthtse du dihydro-4,5 mtthyl-3 dioxo-4,5 naphto[l,2-blfuranne (14b). King et Read (5) avaient dtjB obtenu cette substance par une rnCthode qui s'est avtrte inapplicable B la synthtse des tanchinones. La f a~o n la plus directe d'envisager la prtparation consiste sans doute B introduire dans l'hydroxy-2 naphtoquinone (1) une chaine fonctionnaliste susceptible de se cycliser en rntthyl-3 furoquinone. Puisque ce groupement doit contenir trois atornes de carbone, le propanal ou ses derives sernblaient etre des rtactifs tout designts pour optrer cette transformation. Toutefois, des condensations directes entre l'hydroxy-2 ou la chloro-3 mtthoxy-2 naphtoquinone et le propanal en prtsence de NaH ne donntrent aucun rtsultat utile.Une observation inCdite sur la reaction de quinones avec certains halogtnures d'alkyles sernblait offrir quelqu'espoir de succks par la condensation de l'hydroxy-2 naphtoquinone et d u bromo-2 propanal. Une premikre tentative ne conduisit qu'B une faible quantitt de dihydro-4,5 mtthyl-2 dioxo-4,5 naphto[l,2-blfuranne (2) obtenu sans doute par la cyclisation de l'hydroxy-3 (brorno-2 proptny1)-2 naphtoquinone intermediaire, une rtaction analogue B celle observte par Hooker (6). I1 s'agit, B notre connaissance, du premier cas d e condensation de ce genre avec des aldehydes a-halogtnts et d'un exemple rare d e synthtse directe d'une furoquinone B partir d'une hydroxyquinone. Un second assai, effectut avec le m&me aldehyde en prtsence de HBr, donna un melange...

Hydroxyquinones: Synthesis and Reactivity

“…Analogous methodology was successfully employed for the synthesis of 2-hydroxy-5-methoxy-3-(8', Z, 11' Z)-pentadeca-8', 11',14',-trienyl-1,4-benzoquinone, a host germination stimulant for striga asiatica (witchweed) [9]. Experimental modifications of the method for the preparation of more conventional hydroxyquinones, such as 2-hydroxyphenanthrene-1,4-quinone, can be found in later publications [10,11].…”

“…For this reason the cyclization of hydroxyquinones to the corresponding furan derivatives consists one of the most interesting features of their chemistry and several cyclization methods have been developed. The reaction of lawsone with 2-bromopropanal afforded the ortho-quinone furo derivative, 92, through the initial alkylation of C-2 [11]. (Scheme 42)…”

An Expedite Synthesis of Some Angularly Fused Novel ‘U’‐Shaped Tetracyclic Furophenanthraquinones Simulating ABCD Rings of Isotanshinone‐II

“…(Figure 2) supposed to be responsible for Dan Shen's broad spectrum pharmacological and pharmacoki-netic activities and as a result a large number of studies on the synthesis of furo [1,2-b]phenathraquinones have been made in last few decades. [1,[16][17][18] Naturally occurring 'S'-shaped furoquinone was first extracted by Nakao and Fukushima [19] from Dan Shen as early as in 1934, while isotanshinone-II (naturally occurring 'U'-shaped tetracyclic furoquinone) and dihydroisotanshinone-II have been isolated in very negligible amount only in 1999 by Nagy and his coworkers [20] (Figure 1) from another salvia species (Salvia glutinosa). Consequently compared to large amount of synthetic and biological studies with 'S'-shaped furoquinone derivatives (Tanshinone-I and II derivatives), [17,18] in last few decades, relatively very few synthetic methodologies [17] are available so far for the synthesis of the isomeric 'U'-shaped tetracyclic furophenanthraquinones (phenanthro [4,3-b]furan-4,5-dione) derivatives.…”

Studies on polynuclear furoquinones. Part 1: Synthesis of tri- and tetra-cyclic furoquinones simulating BCD/ABCD ring system of furoquinone diterpenoids

“…In comparison only very few syntheses of tricyclic furoquinone 18 [29–30] and its derivatives [31–33] have been reported. Encouraged by the broad spectrum biological activity of furoquinones, we aimed to synthesize novel polynuclear furoquinones.…”

“…We have not come across any synthesis of phenanthro[1,2- b ]furo-10,11-dione ( 13 ) (the nuclear core structure of Tanshinone-I) though a number of syntheses of naturally occurring tetra cyclic furoquinone diterpenoids have been reported in literature [ 18 – 27 ] in the last few decades. In comparison only very few syntheses of tricyclic furoquinone 18 [ 29 – 30 ] and its derivatives [ 31 – 33 ] have been reported. Encouraged by the broad spectrum biological activity of furoquinones, we aimed to synthesize novel polynuclear furoquinones.…”