Premium
Synthese von zwei natürlich vorkommenden Lactonen mit 10gliedrigen Ringen: (±)‐Phoracantholid J und I
Author(s) -
Gerlach Hans,
Künzler Peter,
Oertle Konrad
Publication year - 1978
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19780610404
Subject(s) - chemistry , saponification , medicinal chemistry , ring (chemistry) , yield (engineering) , diazomethane , organic chemistry , materials science , metallurgy
Synthesis of Two Naturally Occurring 10‐Membered Ring Lactones: (±)‐Phoracantholide J and I Two 10‐membered ring lactones 7 and 11 from the metasternal secretion of the eucalypt longicorn Phoracantha synonyma have been synthesized by the following method. Reaction of the dilithium derivative of 4‐pentynoic acid ( 3 ) with 4‐tetrahydropyranyloxy‐1‐pentylbromide ( 2 ), followed by removal of the protecting group and by esterification with diazomethane, gave methyl 9‐hydroxy‐4‐decynoate ( 4 ; s. Scheme 1 ). Partial hydrogenation of the triple bond in 4 with Lindlar palladium catalyst, followed by saponification lead to cis ‐9‐hydroxy‐4‐decenoic acid ( 6 ). The 9‐hydroxydecanoic acid ( 9 ) was synthesized by addition of methyl magnesium iodide to methyl 8‐formyloctanoate ( 8 ) followed by saponification (s. Scheme 2 ). The hydroxy acids 6 and 9 were converted into the S ‐(2‐pyridyl) thioesters and cyclized in dilute benzene solution under the influence of silver ions to yield (±)‐phoracantholide J ( 7 ) and I ( 11 ) in 74 and 71% yield, respectively.