126410-45-5Relevant articles and documents
Strategies, Setbacks, and Successes in the Synthesis of (-)-Spiroleucettadine
Lamb, Richard A.,Lucas, Nigel T.,Lessene, Guillaume,Hawkins, Bill C.
, p. 10120 - 10133 (2018)
Various strategies toward the synthesis of the marine natural product (-)-spiroleucettadine are described. In the original strategy, a biomimetic inspired oxidation of a 2-imidazoline scaffold uncovered unexpected reactivity, where benzylic oxidation followed by a Baeyer-Villiger reaction was observed. The second generation approach examined oxidative dearomatization of the phenol ring system first, where a competing spirocyclization process was uncovered. Efforts to forge the scaffold via a carbocation mediated benzyl migration were unsuccessful. Highlights of the successful synthesis include two consecutive hypervalent iodine reactions: the first formed the spirocyclic center and the second facilitated installation of an acetate group at the C-5 position to allow for subsequent introduction of the methyl amine side chain.
Total Synthesis of (?)-Spiroleucettadine
Lamb, Richard A.,Aberle, Nicholas S.,Lucas, Nigel T.,Lessene, Guillaume,Hawkins, Bill C.
, p. 14663 - 14666 (2017/10/25)
One of a number of intriguing new alkaloids isolated from the Leucetta sp. sponge in 2004, spiroleucettadine displayed unique structural features on a restricted scaffold: a trans-fused 5,5-bicyclic ring system together with an amino hemiketal moiety. Attempts to synthesize the initially proposed structure failed, raising questions as to its veracity, and structure revision ensued in 2008; no successful synthetic approach has been reported to date. Herein, we describe the enantiospecific total synthesis of (?)-spiroleucettadine by a highly efficient biomimetic approach starting from l-tyrosine. One of two key hypervalent-iodine-mediated oxidation reactions forged the spirocyclic center, and the other enabled the installation of the methylamine side chain in the penultimate step. Our approach provides synthetic access to a new class of spiroannulated natural products and will enable future studies of the structure–biological-activity relationships of these antibacterial compounds.
Pyrrole-based scaffolds for turn mimics
Ko, Eunhwa,Burgess, Kevin
supporting information; experimental part, p. 980 - 983 (2011/04/22)
Two amino acid derived synthons were combined to give homopropargylic amines 2. Platinum dichloride was used to cyclize these intermediates into pyrroles 3 which collapsed to the target secondary structure mimics 1 on treatment with base. Side chains of these compounds overlay with an idealized type 1 β-turn and with an inverse γ-turn.(Figure Presented)
