Lamellarin D

Lamellarins are a group of pyrrole alkaloids first isolated in 1985 from the marine mollusk Lamellaria in the waters of Palau.

Lamellarin D, for example, displays strong cytotoxic activity against tumor cell lines, and is a potent topoisomerase I inhibitor.

[2] The lamellarins all contain a central pyrrole ring, substituted at the 3 and 4 positions by polyhydroxy- or methoxyphenyls.

[3] The lamellarins have been synthesized by a number of groups, including Isibashi, Steglich, Ruchirawat, Banwell, Alvarez, Gupton, Boger, and Handy.

[5][6] The Banwell group’s synthesis of lamellarin K includes an intramolecular azomethine ylide cyclization.

1997 - Lamellarin K synthesis by Banwell: (i) nBuLi, THF, -78 °C, 0.83 h; ZnCl 2 , -78 °C -> 18 °C, 1 h; aryliodide, Pd(PPh 3 ), 18 °C, 4 h (ii) ClCH 2 CH 2 Cl, 18 °C, 7 h; Hunig’s base, 83 °C, 32 h (iii) AlCl 3 , CH 2 Cl 2 , 18 °C, 2 h
1997 Lamellarin G Trimethyl Ether Synthesis by Steglich: (i) 1. -70 °C, 2 eq. nBuLi; 2. 0.5 eq. I 2 , -70 °C -> RT (ii) Mol sieves, 12h, RT (iii) EtOAc, 1 eq. Pb(OAc) 4 , reflux (iv) CH 3 CN, PPh 3 , NEt 3 , Pd(OAc) 2