51918-98-0

Upstream product

• 72541-00-5 6-epi-teucvin 
• 68370-49-0 montanin-A 
• 77265-12-4 C₂₃H₂₆O₈ 
• 64756-04-3 19-acetylgnaphalin 
• 136176-61-9 (12S,20S)-7α-Acetoxy-20-O-acetyl-6,18;15,16-diepoxy-19-norneoclerodane-4(18),5,13(16),14-tetraene 20,12-hemiacetal 
• 70544-90-0 gnaphalin 
• 77265-11-3 C₂₁H₂₄O₇ 
• 136176-66-4 (12S)-15,16-Epoxy-19-norneoclerodane-4,13(16),14-trien-18,6α-olide 20,12-hemiacetal 
• 1378319-21-1 C₁₇H₂₂O₄ 
• 1378319-20-0 C₁₆H₂₀O₃ 
• 22037-28-1 3-bromofurane 
• 1378319-36-8 C₁₆H₂₀O₅ 
• 54168-74-0 isoteuflin 
• 136176-62-0 (12S,20S)-7α-Acetoxy-20-O-acetyl-15,16-epoxy-19-norneoclerodane-4,13(16),14-triene 20,12-hemiacetal 6α,18-methyl acetal 

Relevant academic research and scientific papers

Transformation of Neoclerodane Diterpenoids into 19-Norneoclerodane Derivatives

The neoclerodane diterpenoid eriocephalin (1) was transformed into its 19-nor derivatives 3 and 4 by reaction with potassium tert-butoxide in THF, whereas with the same treatment compound 6 yielded only the transacetylation derivative 7.These results indicated that 19-acetoxy-4α,18-epoxy-7α-hydroxy-6-oxoneoclerodane derivatives are transformed into the corresponding 19-nor compounds in a retroaldol reaction by loss of the C-19 carbon as formaldehyde followed by opening of the oxirane ring and intramolecular attack by a C-18 alkoxide on the carbonyl C-6 carbon atom, giving the allylic hemiacetal 3, which is easily dehydrated to the furanic derivative 4.Compound 4 was transformed into the α,β-unsaturated γ,δ-enol γ-lactone 8 by an oxidation reaction with atmospheric oxygen in chloroform solution.Alternatively, it gave the α,β-unsaturated γ-lactone 11 under acid catalysis.These reactions allowed the partial syntheses of the naturally occurring diterpenoids teuscorolide (9) and teucvin (12) and are of interest for chemical transformations of substances of this kind.

The Absolute Stereochemistry of some Clerodane Diterpenoids from Teucrium Species

The absolute configurations of 19-acetylgnaphalin, and another diterpenoid from T.gnaphalodes, probably identical with teucrin P1, have been determined by X-ray analysis; they belong to the neoclerodane series.Isofruticolone has also been shown to belong to this series.

Total synthesis of (-)-teucvidin

A concise enantioselective synthesis of (-)-teucvidin has been achieved. Our synthetic strategy involved the diastereoselective Michael/Conia-ene cascade cyclization reaction for rapid establishment of the cis-decalin skeleton with three new stereogenic centers in one pot (72%, single diastereomer), the epoxidation/dealkoxycarbonylation protocol for construction of the fused furanone moiety, and the O-allylation/Claisen rearrangement protocol for construction of the all-carbon quaternary center at C9 of the clerodane skeleton.

NEO-CLERODANE DITERPENOIDS FROM TEUCRIUM CANADENSE

From the aerial parts of Teucrium canadense two new neo-clerodane diterpenoids, 18-acetylmontanin D and isoteuflin, have been isolated, besides the previously known diterpenes teucvidin, teuflin, teucvin, 12-epiteupolin II, teuscorodal and (12R)-teupolin I.The structures of 18-acetylmontanin D (18-acetoxy-4α,19;15,16-diepoxy-6β-hydroxy-neo-cleroda-13(16),14-dien-20,12S-olide) and isoteuflin (15,16-epoxy-19-nor-neo-cleroda-5(10),13(16),14-triene-18,6β;20,12S-diolide) were established by chemical and spectroscopic means.The isolation of isoteuflin from T. canadense is of biogenetic importance, since it was previously postulated as the intermediate in the biosynthesis of teucvidin and until now only known as a synthetic compound.Key Word Index - Teucrium canadense; Libiatea; diterpenoids; neo-clerodane derivatives.

MALLOTUCIN C AND D, TWO DITERPENIC LACTONES FROM MALLOTUS REPANDUS

Investigation on the constituents of the titled plant collected in June resulted in the isolation of mallotucin B and mallotucins C and D (as acetates).Mallotucin A (=teucvin), which is the only diterpenic constituent in the plant collected in December, was not detected.Structures of mallotucins C and D were elucidated on the basis of their chemical correlation with mallotucin A and the detailed spectral analyses of their acetates.Mallotucin A is suggested to be biosynthesized from chettaphane-type precursors, mallotucins B, C and/or D.