Remote Hydroxylation of Methyl Groups by Regioselective Cyclopalladation. Partial Synthesis of Hyptatic Acid-A

Abstract

Hyptatic acid-A (32), a 2alpha,3beta,24-trihydroxyolean-12-en-28-oic acid, previously isolated from Hyptis capitata, was obtained from maslinic acid (2). The regioselective cyclopalladation of the axial methyl group on C-4 of maslinic acid afforded the C-24 hydroxymethylene group due to the presence of a C-2-OR substituent. Nevertheless, hederagenin (7) (23-hydroxy derivative) was formed when this oxygenated group was not present.

Antibacterial compounds from Planchonia careya leaf extracts

“…The 1 H and 13 C NMR spectroscopic signals for Compound 4 were consistent with an oleane-type triterpene, and were identified as 2␣,3␤,24-trihydroxyolean-12-en-28-oic acid (hyptatic (Yamagishi et al, 1988;Garcia-Granados et al, 2007). The ␣ and ␤ configurations of the hydroxyl groups on C-2 and C-3, respectively, were confirmed by the large coupling constant, J 2-3 = 10 Hz, attributable to a diaxial proton formation, as well as comparison of the 1 H NMR data with those of the configurational studies carried out on oleanene-type triterpene by Kojima and Ogura (1989).…”

Alcohols or Masked Alcohols as Directing Groups for C–H Bond Functionalization

“…For example, 1,3-diol moiety can be efficiently installed from monoalcohols in three steps without the need to purify any intermediates in spite of the complexity of these substrates (Scheme 16). 21 …”

Scavenging Effect of Various Extracts of the Gymnema sylvestre R. Br. and Antioxidant Activity of the Isolated Triterpenes

“…Triterpenes 1-4, 6 and 13 were identified as 3,16,28-trihydroxyolean-12-ene (1) [17], 3162128-tetrahydroxyolean-12-ene (2) [18], 3,16,22,28-tetrahydroxyolean-12-ene (3) [19], 323,28-trihydroxyolean-12-ene (4) [20], 3,16,21,23,28-pentahydroxyolean-12-ene (6) [21], 316,30-trihydroxylupane (13) [22], and triterpenes 5, 7-12 [23][24][25] were identified as 3162123-tetrahydroxyolean-12-ene (5), 3162123,28-pentahydroxyolean-12-ene (7), 31623,28-tetrahydroxyolean-13,18-ene (8), 1623,28-trihydroxyolean-12-en-3-one (9), 162123,28-tetrahydroxyolean-12-en-3-one (10), 16212223,28-pentahydroxyolean-12-en-3-one (11) and 31623,28-tetrahydroxylupane (12).…”