Synthesis of gamma-butyrolactams by photoinduced PhSe group transfer radical cyclization and formal synthesis of (+/-)-isocynometrine with diphenyldiselenide as promoter.
We have developed a strategy for constructing nitrogen heterocycles by photoinduced PhSe group transfer radical cyclization. trans-Alpha,beta-disubstituted gamma-butyrolactams (2-pyrrolidinones) were prepared in good yields (38-73%) with high regioselectivity and stereoselectivity from N-alkenyl alpha-PhSe beta-keto amides. Reaction outcomes were modulated by the steric effect of the substituents on the nitrogen atom of the cyclization precursors and the stereoelectronic effect of the substrates. Diphenyldiselenide, as an additive, was found to promote ring closure. The advantage of this strategy in natural product synthesis is demonstrated by a formal synthesis of (+/-)-isocynometrine.
Yang
Dan
D
Department of Chemistry, Fudan University, Shanghai 200433, China. yangdan@hku.hk
Lian
Gao-Yan
GY
Yang
Hai-Feng
HF
Yu
Jin-Di
JD
Zhang
Dan-Wei
DW
Gao
Xiang
X
D015107:4-Butyrolactone / Q000031:analogs & derivatives / Q000138:chemical synthesis* / Q000737:chemistry; D000470:Alkaloids / Q000138:chemical synthesis* / Q000737:chemistry; D003500:Cyclization; D005609:Free Radicals / Q000737:chemistry; D007093:Imidazoles / Q000138:chemical synthesis* / Q000737:chemistry; D015394:Molecular Structure; D016566:Organoselenium Compounds / Q000737:chemistry*; D010777:Photochemistry; D013237:Stereoisomerism
D000470:Alkaloids; D005609:Free Radicals; D007093:Imidazoles; D016566:Organoselenium Compounds; C445724:isocynometrine; D015107:4-Butyrolactone