Total Synthesis of Brevetoxin B. 3. Final Strategy and Completion

Autor:	Floris P. J. T. Rutjes, M. Sato, E. Untersteller, Kyriacos C. Nicolaou, Emmanuel A. Theodorakis, J. Tiebes
Rok vydání:	1995
Předmět:	chemistry.chemical_classification Allylic rearrangement Stereochemistry Diol Total synthesis Epoxide General Chemistry Ring (chemistry) Biochemistry Aldehyde Catalysis chemistry.chemical_compound Colloid and Surface Chemistry chemistry Wittig reaction Side chain
Zdroj:	Journal of the American Chemical Society. 117:10252-10263
ISSN:	1520-5126 0002-7863
Popis:	The final strategy for the total synthesis of brevetoxin B (1) according to the retro synthetic analysis shown in Scheme 1 is described. Starting with the tetracyclic ring system 8 (DEFG), the construction of the C ring was accomplished via an intramolecular conjugate addition (7 — 13). A hydroxy epoxide cyclization was then utilized for the formation of ring B (6 —^ 21). Ring A was introduced via an intramolecular phosphonate ester—ketone condensation (5 -*• 27) to produce, after side chain elaboration, the desired heptacyclic phosphonium iodide 4. Formation of the tricyclic aldehyde 3 (UK) starting from diol 34 is also described. Wittig coupling of 3 and 4 followed by selective deprotection, hydroxy dithioketal cyclization, and radical desulfurization produced the undecacyclic system 48 representing the complete brevetoxin B skeleton (46 — 2 — 47 — 48). Allylic oxidation of ring A (48 49) followed by side chain elaboration of the K ring side chain (49 — * 50 —■ 51 — * 52) led to the TBS protected brevetoxin B (52) which upon exposure to HF*pyridine treatment afforded natural brevetoxin B (1).
Databáze:	OpenAIRE
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