Synthetic Transformations of Higher Terpenoids. XXXIII.* Preparation of 15,16-Dihydroisopimaric Acid and Methyl Dihydroisopimarate and their Transformations

Efficient Synthesis of the N‐(buta‐2,3‐dienyl)carboxamide of Isopimaric Acid and the Potential of This Compound towards Heterocyclic Derivatives of Diterpenoids

“…As the starting compound, we used the N-propargyl amide of isopimaric acid, that is, compound 2,w hich was obtained on a gram scale in two steps from isopimaric acid. [10] The CuI-mediated reaction of terminal alkyne 2 with formaldehyde in the The N- (2,3-butadienyl)carboxamideo fi sopimaric acid, that is, compound 3,w as prepared through at wo-step synthetic procedure startingf rom the natural diterpene isopimaric acid. The Pd-catalyzed cross-coupling and subsequent cyclization of terpenoid allene 3 with severala ryl iodides and aryl bromides gave access to optically active diterpenoid-oxazoline derivatives in good to excellent yields.…”

“…The addition of MeCN to the solvents ystem resultedi nadecrease in the selectivity and an increase in the yield of tetrahydrobenzopyran 11 c (Table 2, entry 7). So, the effectiveness of the palladacycle catalyst (Herrmann-Beller palladium catalyst) was demonstrated in the coupling-cyclization reactions of terpenoid allene 3 with 2-iodophenol (10).…”

“…The starting materials 4-iodobenzonitrile (4a), 1-iodo-3-(trifluoromethyl)benzene (4b), iodobenzene (4c), 1-iodo-2-methoxybenzene (4d), 1-iodo-3-methoxybenzene (4e), 1-iodo-4-methoxybenzene (4f), methyl 2-acetamido-5-bromobenzoate (4g), 2-hydroxy-5-iodo-3-methoxybenzaldehyde (4h), 2-iodopyrazine (4i), tert-butyl (2-iodophenyl)carbamate (6) ChemistryOpen 2018, 7,890 -901 www.chemistryopen.org isolated from Pinus sibirica R. Mayr sap by the reported method. [10] Solvents (1,4-dioxane, acetonitrile, DMF,a nd CH 2 Cl 2 )w ere purified by standard methods and were distilled in as tream of argon just before use. CHCl 3 ,e ther,p etroleum ether (refers to al ight petroleum fraction, b.p.…”

“…25, 60.32 (2 C-4'), 79.50, 79.61 (2 C-5'), 109.08 (2 C-16), 111.79, 112.11( 2C-7'), 120.91, 121.06 (2 C-7), 126.36, 126.36 (4 C-2'',6''), 127.84 (2 C-4''), 128.32 (4 C-3'',5''), 135.43 (2 C-8), 137.81, 137.91 (2 C-6'), 147.18 (2 C-1''), 150.16 (2 C-15), 173.97, 174.12 ppm (2 C-2');IR: ñ = 2927IR: ñ = , 2869IR: ñ = , 2850IR: ñ = , 1650IR: ñ = , 1500IR: ñ = , 1384IR: ñ = , 1234IR: ñ = , 1139IR: ñ = , 1105IR: ñ = , 1031 4aR,4bS,7S,10aR) -1,4a,7-trimethyl-7-vinyl-1,2,3,4,4a,4b,5,6,7,8,10, (m, 10 H, 2H-11, 6, 2, 12, 2), 1. 68-1.78 (m, 4H,2 H-6, 9),1.79-2.03 (m, 10 H, 2H-1, 14, 14, 3, 5) 2869, 2846, 1648, 1598, 1500, 1461, 1436, 1384, 1292, 1247, 1240, 1182, 1139, 1126, 1095, 1047, 1027, 985, 912, 870, 754 cm (1R,4aR,4bS,7S,10aR) 4a,2,3,4,4a,4b,5,6,7,8,10, (m, 2H,2H-11), 1.32 (s, 3H,C 19 H 3 ), 1.34 (s, 3H,C 19 H 3 ), 1.31-1.39 (m, 2H,2H-12), 1.44-1.49 (m, 2H,2H-12), 1.52-1.68 (m, 10 H, 2H-11, 2, 3, 2, 6), 1.70-1.78 (m, 4H,2H-6, 9), 1.82-2.01 (m, 10 H, 2H-1, 14, 14, 3, 5) 6 Hz,1H,4.91 (dd,J = 17.7,1.6 Hz,1H,4.92 (dd,J = 17.7,1.6 Hz,1H,4H,5'), 5.32 (s, 2H, =CH 2 ), 5.34 (s, 2H, =CH 2 ), 5.36 (s, 1H, =CH 2 ), 5.76 (dd,…”

“…For example,i sopimaric acid (1)i sareadily available and versatile tricyclic diterpenoid that is well represented in the resin of conifers of the genera Pinus, Larix,a nd Picea. [3,4] The attraction of compound 1 as ab iorenewable compound and its interesting biological and pharmaceutical properties, whichi nclude anti-bacterial, [5][6][7] antiviral, [8] anda nti-inflammatory [9] activities, has stimulated the development of av ariety of chemistries for functionality,i ncluding oxidative [10][11][12] and isomeric [13] transformations, in addition to several modificationso ft he carboxyl group. [14,15] The number of examples in the literature detailing the functionalization of isopimaric acid is limited,a nd they do not result in the generation of evolvable libraries of compounds for structure-activity relationship studies.…”