Myrmicarin 217 is a tricyclic alkaloid recently discovered in the poison glands of Myrmicaria ants, a genus of african Myrmicinae. As a pyrrolo[2,1,5-cd]indolizidine, Myrmicarin 217 belongs to the izidine type alkaloids, largely present in the nature and characterized by a variety of physiological activities. We recently found a new approach to 5,6-dihydroindolizines via in situ domino hydroformylation/cyclization/dehydration reactions sequence of 1-allylpyrroles. In this pathway an unprecedented intramolecular electrophilic substitution by the carbonyl group of the produced 4-pyrrolylbutanals on C2 pyrrole carbon atom is the key step to construct the six-membered ring of the indolizine moiety. The 4-pyrrolylbutanals are a class of compounds almost unknown in literature, perhaps because they are very reactive or difficult to be prepared via traditional organic chemistry. Encouraged by the success of our protocol and attracted by the intriguing structure of the above alkaloid, we tried to synthesize non racemic Myrmicarin 217 via the cyclodehydration of the chiral (4S)-(+)-4-carboxyethyl-4-(pyrrol-1-yl)butanal.
Intramolecular cyclodehydration of (4S)-(+)-4-carboxyethyl-4-(pyrrol-1-yl)butanal as the key step in the formal synthesis of (S)-(-)-Myrmicarin 217
Settambolo R;
2003
Abstract
Myrmicarin 217 is a tricyclic alkaloid recently discovered in the poison glands of Myrmicaria ants, a genus of african Myrmicinae. As a pyrrolo[2,1,5-cd]indolizidine, Myrmicarin 217 belongs to the izidine type alkaloids, largely present in the nature and characterized by a variety of physiological activities. We recently found a new approach to 5,6-dihydroindolizines via in situ domino hydroformylation/cyclization/dehydration reactions sequence of 1-allylpyrroles. In this pathway an unprecedented intramolecular electrophilic substitution by the carbonyl group of the produced 4-pyrrolylbutanals on C2 pyrrole carbon atom is the key step to construct the six-membered ring of the indolizine moiety. The 4-pyrrolylbutanals are a class of compounds almost unknown in literature, perhaps because they are very reactive or difficult to be prepared via traditional organic chemistry. Encouraged by the success of our protocol and attracted by the intriguing structure of the above alkaloid, we tried to synthesize non racemic Myrmicarin 217 via the cyclodehydration of the chiral (4S)-(+)-4-carboxyethyl-4-(pyrrol-1-yl)butanal.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
