Tetrodotoxin from levoglucosenone

Easily prepared from glycols, enones have been investigated as dienophiles. They react with butadiene under Lewis acid catalysis to form chiral cyclohexenes used in the synthesis of compactin analogs [353]. Levoglucosenone has been used in a Diels-Alder reaction with acetoxy-butadiene to construct a part of the indole alkaloid reserpine [354], and in synthetic studies toward tetrodotoxin [355]. Analogs of the anthracycline rhodomycinone have been similarly prepared [356]. [4 + 2]-Cycloaddition of the same enone with silyloxydiene allowed the creation of the fused ring system present in actinobolin [357]. 

Some interesting examples of levoglucosenone s application in the synthesis of natural products and rare carbohydrates have been reported (58-81). Indeed, levoglucosenone has been used in the synthesis of (+)-multistriatin (58,72-73), Prelog-Djerassi lactonic acid (58,59) md (-)-a//o-yohimbane (61) The synthesis of indole alkaloid reserpine (61), and serricomin (58), as well as tetrodotoxin (53,62) were also reported from levoglucosenone or its functionalized derivatives and was reviewed earlier by us (1). 

A Diels-Alder reaction between 3-bromo-levoglucosenone and butadiene gives rise to adduct (10), which could be converted into (11), which represents the guanidinium part of tetrodotoxin. An interesting intramolecular Diels-Alder reaction (Scheme 3) was a key step in a synthesis of (+)-isovelleral (12) from the L-erythuronic acid derivative (13) which is accessible from D-ribonolactone. The synthesis produced firstly the diastereomer (14) of (-f-)-isovelleral (12), but the two were thermally interconvertible by an ene-type opening and closing of the three-membered... 

---

See also in sourсe #XX -- [ , , , ]

See also in sourсe #XX -- [ , , , ]

---