Cover Picture: Total Synthesis of Palau’amine (Angew. Chem. Int. Ed. 6/2010)

Asymmetric Synthesis of Axinellamines A and B

“…We thus switched to developing a new route with an early introduction of the chloride despite its reported hydrolytic instability. [5,9,10,18,19] Using azidoimidazole 5 (prepared in 10 steps from (S)-Garner's aldehyde) [14,15] as the common intermediate for 1 and 2a, the synthesis of axinellamines (1) commenced with the selective reduction of the azido group on the imidazole ring and epimerization of the C12 stereocenter (Scheme 1). We found that the imidazoyl azide of 5 could be reduced immediately upon addition of triphenylphosphine at room temperature, whereas the alkyl azide would not react until warming the reaction mixture to 40°C.…”

“…Recently, Romesberg, Baran, and co-workers have found that 1a and 1b display promising activity against both Gram-positive and Gram-negative bacteria and 1a causes membrane destabilization in Escherichia coli. [3] Among several labs that study the synthesis of dimeric pyrroleimidazole alkaloids 1-3, [3][4][5][6][7][8][9][10][11][12][13][14][15][16] Carreira et al reported the first synthetic strategy directed towards 1 [6] using a Diels-Alder reaction to establish its fully functionalized cyclopentyl core. Romo and co-workers subsequently disclosed an oxidative ring-contraction approach that was inspired by Scheuer's biosynthetic hypothesis.…”

“…This approach has enabled the asymmetric synthesis of not only 1, [4] but also massadines (2), [9] and palau'amine (3). [10] They subsequently developed a second-generation synthesis wherein the cyclopentyl core of 1 was assembled by a Pauson-Khand reaction. [3,5] This new approach has further allowed for the gramscale synthesis of 1.…”

Biomimetic Synthesis of Marine Pyrrole‐2‐Aminoimidazole and Guanidinium Alkaloids

“…The synthesis of dihydrooroidin (30) was achieved in five steps and 35% overall yield starting from l-citrulline. It began with the preparation of 2-aminoimidazole-4-propanamine (31) from citrulline.…”

Total Synthesis of Palau’amine

“…Not surprisingly, although many attempts to synthesize palau amine and related compounds have been reported, and numerous reviews of these different approaches have been published. 5 Until our report in 2015, 6 there had been only one report of a total synthesis, by Baran s group in 2010, 7 which was followed by the development of an asymmetric version in 2011. 8 The most dif cult challenge in the total synthesis of 1 is the construction of a trans bicyclo[3.3.0]octane system that corresponds to the D/E ring junction, and Baran s group addressed this by adopting a transannular reaction of 9 membered lactam 2, named macro palau amine, leading to 1 in the nal step ( Figure 1a).…”