Towards stereochemical control: A short formal enantioselective total synthesis of pumiliotoxins 251D and 237A

• Jie Zhang,
• Hong-Kui Zhang and
• Pei-Qiang Huang

Beilstein J. Org. Chem. 2013, 9, 2358–2366, doi:10.3762/bjoc.9.271

• ; ring closure; trans-methylation; Introduction Pumiliotoxins (PTXs, 1, Figure 1) such as pumiliotoxin 251D (2) are a subclass of indolizidine alkaloids isolated from the skin secretion of neotropical frogs. A total of 19 members have been isolated and partially characterized [1]. Pumiliotoxins are

• an equatorial attack of the nucleophile giving the cis-product would be preferable. Indeed, Holmes and co-workers have reported that methylmagnesium bromide addition to N-Cbz-protected piperidin-3-one 8 produced exclusively the trans-methylation product 9 [44] (Scheme 3). In that case, the N