Stereoselective Total Synthesis of Bistramide A

Abstract

A highly stereoselective and convergent total synthesis of bistramide A is described. The salient feature of this synthesis is the construction of the spiroketal subunit by hydrolysis of dialkylated tosylmethyl isocyanide derivative derived via alkylation of TosMIC with suitably substituted halohydrin derivatives.

Understanding the Reactivity of Acyl Anion Equivalents: The Epoxide Ring Opening Case

“…27 and 28) anions (Scheme 3), [55] but manipulation of these AAEs was fraught with difficulty. Protection of 31 as the TBS ether 33, however, proceeded in good yield (73 %) and subsequent coupling to 1-iodopropane [56] also occurred affording 34 in high yield (83 %, Scheme 3).…”

“…Whereas a 1,2-disubtituted epoxide only gave a low yield (Entry 6, Table 2), cyclic disubstituted epoxides are good substrates (Entries 7 and 8, Table 2) although cyclooctene oxide (Entry 9, Table 2) surprisingly failed to react at all. The TBS protection and the ensuing second substitution with propyl iodide [56] proceeded in moderate to excellent yields (Scheme 4; Table 2). Unmasking the keto group from a disubstituted TosMIC derivative of type 39 has been reported and will not be replicated here.…”

“…Unmasking the keto group from a disubstituted TosMIC derivative of type 39 has been reported and will not be replicated here. [55][56][57] Furthermore, although the anion of propyl-substituted TosMIC is reported to undergo substitution reactions with alkyl halides, [58] we found that in the case of epoxide ring opening, utilizing our optimized conditions, no reaction occurred. It should be noted that this work has not considered "two stage" masked AAEs as alternatives (i.e.…”

A Concise Synthesis of (–)‐ and (+)‐trans‐Whisky Lactones

“…Chiral γ-butyrolactones are not only useful starting materials for various bioactive compounds, [1] but also act as core elements of many potentially useful natural products, [2] e.g. whisky lactones and cognac lactones in wine and other alcoholic beverages, [3] (-)-muricatacin isolated as the major component of a scalemic mixture from the seeds of annona muricata, [4] (-)-japonilure [5] and (+)-eldanolide [6] pheromones of the Japanese beetle and African sugarcane borer all have a γ-butyrolactone unit (Scheme 1).…”

A Stereoselective Synthesis of the C(13)-C(23) Fragment of Iriomoteolide-1b

“…随后的发生化合物 12 中的手性辅基脱除 [9] , 对甲基苯磺 酰氯单保护, 氢化铝锂还原, 二甲基叔丁基硅氯保护得 到 13a. 在臭氧化反应中, 往反应体系加入硼氢化钠可 以一锅得到 13b, [10] 接着发生 Mitsnobu 反应和氧化反应 得 到 化 合 物 6. 在 我 们 尝试 了 很 多 条 件 后 发 现 , 在 DME/THF (V ∶ V ＝ 1 ∶ 1) 混 合 溶 剂 中 进 行 Julia-Kocienski [11] 反应可以得到较好的结果, 但是确定不了形成 的双键的构型, 我们将化合物 3 进行 DIBAL-H 还原得 到 E-4 [12] , 得到的双键构型单一.…”