Victor Lee

Studies on the Biomimetic Synthesis of the Manzamine Alkaloids

Intramolecular Diels–Alder reaction of a simple macrocyclic bis-dihydropyridine precursor 1 resulted in the formation of a complex marine alkaloid keramaphidin B, thus verifying a biosynthetic theory.

A Short Biomimetic Synthesis of the Meroterpenoids Guajadial and Psidial A

The biosynthesis of the meroterpenoid guajadial was previously hypothesized to occur via a hetero-Diels-Alder reaction between caryophyllene and an o-quinone methide. This hypothesis has been verified via the biomimetic synthesis of guajadial and psidial A in an aqueous three-component coupling reaction, between caryophyllene, benzaldehyde, and diformylphloroglucinol.

Investigations into the Manzamine Alkaloid Biosynthetic Hypothesis

The biomimetic synthesis of a pentacyclic alkaloid (keramaphidin B, 1), an intermediate in the biogenetic pathway to the manzamine alkaloids, has been achieved. Compound 1 was formed by an intramolecular Diels-Alder reaction of macrocycle 2 in buffer followed by reduction with NaBH4 . This reaction provides the first direct expeimental evidence for the authors biosynthetic hypothesis.

Efficient synthesis of the sponge alkaloids cyclostellettamines A-F

Abstract The total synthesis of cyclostellettamines A-F is reported. The synthetic cyclostellettamines were reduced to the neutral bis -tetrahydropyridine compounds, and exact mass measurements of these reduced products provided unequivocal evidence for the cyclostellettamine structures.

Synthesis of a novel thiabicyclo[3.2.0]heptan-6-one analogue of penicillin

Abstract Synthesis of (1SR, 4SR, 5SR, 7RS)-7-(tert-butoxycarbonylamino)-2-thiabicyclo[3.2.0]heptan-6-one-4-carboxylic acid ethyl ester, a novel cyclobutanone analogue of a β-lactam antibiotic is described. This was achieved by [2+2] cycloaddition of a 2,3-dihydrothiophene with dichloroketene, followed by conversion to a cyclobutanol and use of an intramolecular nitrene insertion strategy to install nitrogen functionality at C-7 with endo stereochemistry.

Synthesis and analysis of Leu-enkephalin analogues containing reverse turn peptidomimetics

Abstract the synthesis and 1 H n.m.r. analysis of peptidomimetics of Leu-enkephalin containing bicyclic lactams is described.

Synthesis of a possible structure of pyrinodemin A

Abstract An alternative possible structure of pyrinodemin A is synthesised. The 13 C NMR of the synthetic product 3 is in better agreement with the literature data.

TOTAL SYNTHESIS OF CYTOTOXIC SPONGE ALKALOIDS MOTUPORAMINES A AND B

Abstract The synthesis of two sponge alkaloids, Motuporamines A and B is reported. The key step involved a reductive amination using sodium triacetoxyborohydride.

Total synthesis of cytotoxic sponge alkaloids hachijodines F and G

Abstract The total synthesis of two cytotoxic sponge alkaloids hachijodines F ( 1 ) and G ( 2 ) via a common intermediate 3 is described.

Biomimetic synthesis of marine sponge metabolite spiculoic acid A and establishment of the absolute configuration of the natural product

The synthesis of spiculoic acid A (1) using a biomimetic Diels-Alder reaction is described; comparison of the specific rotation of the natural and synthetic material revealed that the enantiomer of the natural product has been synthesized.