71135-79-0Relevant academic research and scientific papers
Total Synthesis of the Spirans of Cannabis: Cannabispiradienone, Cannabispirenone-A and -B, Cannabispirone, α- and β-Cannabispiranols and the Dihydrophenanthrene Cannithrene-1
Crombie, Leslie,Tuchinda, Patoomratana,Powell, Michael J.
, p. 1477 - 1484 (2007/10/02)
O-Methylcannabispirenone has been synthesised (57percent overall from 3,5-dimethoxycinnamic acid) via 5,7-dimethoxyindanone, p-tolylsulphonylmethyl isocyanide conversion into the 1-nitrile, alkylation with 1-iodo-3,3-ethylenedioxybutane, deacetalisation, and spirocyclisation. 5,7-Dimethoxyindanone is 7-deprotected by boron trichloride with high selectivity, and re-protected as the methoxyethoxymethyl ether: following the above route, finally deprotecting by boron trichloride, gives cannabispirenone-A (2) in 21percent overall yield.O-Methylcannabispirenone can be demethylated to give (2) by lithium 1,1-dimethylethanethiolate: demethylation with boron tribromide gives cannabispirenone-B (3).Hydrogenation of synthetic cannabispirenone-A gives cannabispirone (4), reduced by borohydride to the epimeric α-(6) and β-(5) cannabispiranols, separated by h.p.l.c.Dehydrogenation of O-methylcannabispirenone with dichlorodicyanobenzoquinone, followed by lithium 1,1-dimethylethanethiolate demethylation, gives cannabispiradienone (1).Under acidic conditions, the latter undergoes dienone-phenol rearrangement to give cannithrene-1 (8), thus completing the total synthesis of the spiro-cannabinoid group of natural products discussed in the preceding paper.The unsubstituted cannabispirenone parent has also been synthesised.
1,2-Disubstituted Ethanes As Possible Precursors For The Synthesis of Cannabis Spirans
Crombie, Leslie,Crombie, W. Mary L.,Jamieson, Sally V.,Tuchinda Patoomratana,Whitaker, Alison J.
, p. 1485 - 1492 (2007/10/02)
Three possible methods for converting suitable 1,2-disubstituted ethanes into Cannabis spirans have been investigated. 4',5-Dihydroxy-3-methoxybibenzyl underwent intramolecular o-p- and p-p-coupling with ferricyanide in a chloroform-aqueous potassium carbonate system, but yields were low: certain other oxidants did not succeed or gave only traces of product.A method for making 1-hydroxy-1-(3,5-dimethoxyphenylethyl)cyclohexan-4-one ethylene acetal or thioacetal via a Birch reaction is described: despite favourable precedent, acid-catalysed cyclisation led to octahydrophenanthrenones rather than spiro-ketones, whilst N,N-dimethylformamide dineopentyl acetal gave two olefins.Jacquesy's super-asid method for making spirocyclohexenones from a methoxylated bibenzyl was not applicable to the 3,4',5-trimethoxy-case, which would have given cannabispirenone methyl ether, presumably because of protonation of both aromatic systems.
SYNTHESIS OF THE FIVE NATURAL CANNABIS SPIRANS
Crombie, Leslie,Powell, Michael J.,Tuchinda, Patoomratana
, p. 3603 - 3606 (2007/10/02)
An efficient route to the O-protected spirenones (2c) and (2d) is described: from these, the five known natural spirans of cannabis, i.e. cannabispiradienone (1a), cannabispirenone-A (2a), cannabispirenone-B (2b), cannabispirone (3a) and cannabispiranol (4a), are synthesised.
