Studies on the terpenoids and related alicyclic compounds. XXVI. Total syntheses of highly oxygenated furanoeremophilanes: (.+-.)-6.BETA.-Hydroxy-1,10-dehydrofuranoeremophilan-9-one, (.+-.)-decompositin, (.+-.)-dihydrodecompositin, (.+-.)-adenostylone, (.+-.)-3.BETA.,6.BETA.-dipropionyloxyeuryopsin-9-one, (.+-.)-3.BETA.,6.BETA.-dihydroxy-10.BETA.
作者:KOJI YAMAKAWA、TSUYOSHI SATOH
DOI:10.1248/cpb.29.3474
日期:——
The total syntheses of several highly oxygenated, 1, 10-dehydrofuranoeremophilanes [(±)-6β-hydroxy-1, 10-dehydrofuranoeremophilan-9-one (1a), (±)-decompositin (1b), (±)-dihydrodecompositin (3), (±)-adenostylone (1c), (±)-3β, 6β-dipropionyleuryopsin-9-one (2b)] and polyoxy compounds [(±)-3β, 6β-dihydroxy-10βH-furanoeremophilan-9-one (4), (±)-3β, 6β-dihydroxy-10αH-furanoeremophilan-9-one (5), and 3β-acetoxy-6β-isobutyroxy-furanoeremophilan-9-one (28b)] from a bicyclic enone (6a) are described. Treatment of 10α-hydroxy-6, 9-dioxo compounds (8a, 18 and 23) with SOCl2-pyridine gave the corresponding 1, 10-dehydro-6, 9-dioxo compounds (11, 20 and 24, respectively). NaBH4 reduction of 11, 20 and 24 afforded the 6β-hydroxy derivatives (12a, 1a and 2a, respectively) regio- and stereoselectively. (±)-1a was converted into (±)-1b, (±)-1c, and (±)-3. (±)-2a was also converted into (±)-2b. Catalytic reduction of 12a with H2/Pd gave the 10α-H and 10β-H compounds (25 and 26a). Deketalization of 25 and 26a with aq. AcOH followed by reduction with NaBH4 gave (±)-5 and (±)-4, respectively. Esterification of 26a with 2-methylbutyric anhydride-pyridine gave the ester (26b), which was converted to (±)-28a and 28b.
几种高含氧的 1,10-脱氢呋喃eremophilanes [(±)-6β-hydroxy-1, 10-dehydrofuranoeremophilan-9-one (1a),(±)-decompositin (1b),(±)-dihydrodecompositin (3),(±)-adenostylone (1c),(±)-3β、(2b)]和聚氧化合物[(±)-3β,6β-二羟基-10βH-呋喃右旋苯胺-9-酮 (4),(±)-3β,6β-二羟基-10αH-呋喃右旋苯胺-9-酮 (5) 和 3β-乙酰氧基-6β-异丁氧基-呋喃右旋苯胺-9-酮 (28b)]。用 SOCl2 吡啶处理 10α-hydroxy-6, 9-dioxo 化合物(8a、18 和 23),可得到相应的 1、10-脱氢-6、9-二氧代化合物(分别为 11、20 和 24)。用 NaBH4 还原 11、20 和 24,可得到 6β-羟基衍生物(分别为 12a、1a 和 2a),并具有区域和立体选择性。(±)-1a转化为(±)-1b、(±)-1c和(±)-3。(±)-2a也转化为(±)-2b。用 H2/Pd 催化还原 12a,得到 10α-H 和 10β-H 化合物(25 和 26a)。将 25 和 26a 用 aq.AcOH 脱酮,然后用 NaBH4 还原,分别得到 (±)-5 和 (±)-4。用 2-甲基丁酸酐-吡啶对 26a 进行酯化,得到酯 (26b),并转化为 (±)-28a 和 28b。