Synthesis-Guided Structure Revision of the Sarcodonin, Sarcoviolin, and Hydnellin Natural Product Family

Abstract

A sweeping structural revision of the sarcodonin natural product family (published structures: 1a–13a) is proposed after extensive studies aimed at their chemical synthesis. Key features of revised structure 1b include replacement of the N,N-dioxide moiety with an oxime, ring opening of the central diketopiperazine, and transposition of the terphenyl wing from the 1β-2β position of 1a to the 2β-3β position of 1b. This structure revision arose from the serendipitous synthesis of a benzodioxane aminal (44) whose structure was unambiguously determined by X-Ray crystallography and whose spectral properties bore considerable resemblance to the published data for the sarcodonins. A versatile new method for O-arylation of hydroxamic acids is also reported herein, as well as a manganese(III)-mediated α-oxidation of hydroxamic acids to aminals.

Convergent Synthesis and Structural Confirmation of Phellodonin and Sarcodonin ε

“…To pursue this approach, however, a pyrazine bis - N -oxide had to be prepared as the dienophile, which we had previously been unable to achieve. 4 After further investigation, a synthetic route was devised, and therefore a diketopiperazine of L-isoleucine ( 4 ) was converted into bis -chloropyrazine 6 in three steps using known conditions (Scheme 1). 5 The first N -oxidation of 6 was quite facile; however, the resulting mono - N -oxide 7 was highly deactivated, and vigorous oxidizing conditions were necessary to achieve the second N -oxidation to give 8 in sufficient quantities.…”

Study of the Oxidative Cleavage Proposed in the Biogenesis of Transtaganolides/Basiliolides: Pyran‐2‐one Aromaticity‐Mediated Regioselective Control and Biogenetic Implications

“…m ‐Chloroperbenzoic acid ( m ‐CPBA) is the oxidant commonly used for oxidative cleavage of o ‐quinones, and, before using this reagent on coumarins, we decided to test it with the commercially available 3,5‐di‐ tert ‐butylcatechol ( 1j ) (Scheme ). Its oxidation to 3,5‐di‐ tert ‐butyl‐ o ‐quinone ( 2 ) by using NaIO 4 under biphasic conditions, followed by Baeyer–Villiger reaction with m ‐CPBA[14b] provided the desired 2,4‐di‐ tert ‐butylmuconic anhydride ( 3 ) in 92 % overall yield. The use of zinc powder in glacial acetic acid under ultrasound has been reported for reducing α,β‐unsaturated 1,4‐dicarbonyl units such p ‐quinones, fumarates or maleates into hydroquinones or succinates, respectively .…”

Sarcodon Mushrooms: Biologically Active Metabolites

“…Recently the structures of sarcodonins and sarcoviolins have been revised by synthesis, and the new structure for sarcodonin 12 is reported in Fig. 11 (Lin et al, 2011). It is very interesting to notice that screening the literature with the term "sarcodonin" different structures with the same name have been reported, as we will see checking the compounds isolated from S. scabrosus.…”