A Photorearrangement To Construct the ABDE Tetracyclic Core of Palau’amine

Abstract

A synthesis of the ABDE tetracyclic carbon core of palau'amine was achieved in 9 steps from commercial materials. The core's most notable feature, a highly strained trans cyclopenta[ c]pyrrolidine, was obtained in high yield using a ring contraction strategy starting from a much less strained trans bicyclic lactam derivative that is accessible in only 7 steps.

A Review of the Synthetic Strategies toward Dihydropyrrolo[1,2-a]Pyrazinones

“…The ABDE core of palau'amine was constructed from the dibromide salt of diamine 123 and triscarbonyl compound 124 by a cascade reaction involving a Paal-Knorr pyrrole synthesis, leading to intermediate pyrrole 125, which, after neutralization, undergoes sub sequent lactamization to afford tetracyclic 126 [122] (Scheme 34). In a variant of this three component reaction, 1,2-diaminoethane and ethyl pyruvate are combined at room temperature in acetonitrile, and then α-bromo ketones are added and the mixture heated in the presence of iron (III) chloride to afford 122 via the reaction of intermediate pyrazine 121 with the bromoketone [121] (Scheme 33).…”

“…The ABDE core of palau'amine was constructed from the dibromide salt of diamin 123 and triscarbonyl compound 124 by a cascade reaction involving a Paal-Knorr pyrrol synthesis, leading to intermediate pyrrole 125, which, after neutralization, undergoes sub sequent lactamization to afford tetracyclic 126 [122] (Scheme 34).…”

“…The ABDE core of palau'amine was constructed from the dibromide salt of diamine 123 and triscarbonyl compound 124 by a cascade reaction involving a Paal-Knorr pyrrole synthesis, leading to intermediate pyrrole 125, which, after neutralization, undergoes subsequent lactamization to afford tetracyclic 126 [122] (Scheme 34). often straightforward nature of the ring closing reactions, a wide array of functional groups or substitution patterns can be easily introduced, explaining this being the predominant strategy for the synthesis of pyrrolopyrazinones.…”

Direct additive-free N-formylation and N-acylation of anilines and synthesis of urea derivatives using green, efficient, and reusable deep eutectic solvent ([ChCl][ZnCl2]2)

“…Ureas and their derivatives are extremely significant nitrogen-containing carbonyl compounds that are abundantly present in both natural and manufactured substances 43 . In addition, many biologically active substances bear urea units in their structures such as anti-mycobacterial 44 , 45 , anti-fungal 46 , anti-tumor 47 , 48 , antagonists of natural receptors 49 , and enzyme inhibitors 50 . They have been deeply studied in many fields including infectious diseases such as malaria 51 and tuberculosis 52 , 53 , immunology 54 , oncology 55 .…”

Synthesis of Five-Membered Cyclic Guanidines via Cascade [3 + 2] Cycloaddition of α-Haloamides with Organo-cyanamides

“…For example, saxitoxin, isolated from the toxic mussels Mytilus californianus , is an inhibitor of voltage-gated sodium channels . Palau’amine, a pyrrole-imidazole alkaloid isolated from the marine sponge Stylotella agminata , has garnered much attention due to its significant biological properties such as immunosuppressive and antitumor activities . Imidacloprid is a famous neonicotinoid insecticide for crop protection and animal health usages .…”