- Experimental and theoretical study of the photochemical and thermal decomposition of maleic and dichloromaleic anhydrides
-
The photochemical and thermal behavior of maleic anhydride 1a and dichloromaleic anhydride 1b, in cryogenic matrix were investigated by means of FT-IR spectroscopy. The ketenylcarbenes represent the key intermediate in the decomposition processes of the a
- Ionescu,Pietri,Hillebrand,Monnier,Aycard
-
-
Read Online
- Cyclopropenones in the synthesis of indolizidine, pyrrolo[2,1-a]isoquinoline and indolizino[8,7-b]indole alkaloids
-
An attempted synthesis of the indolizidine natural product castanospermine resulted in the successful addition of cyclopropenone to a sugar-derived poly-hydroxylated cyclic imine to give an indolizidinone product, but with the installation of an extra hydroxy group at the castanospermine 8a-bridgehead position. This was also observed in our previous approach to the australine and hyacinthacine pyrrolizidine natural products. The same oxidative phenomenon occurred during the synthesis of pyrrolo[1,2-a]isoquinolines from the reaction of aldimine dihydroisoquinolines with cyclopropenones, whereas ketimine based dihydroisoquinolines gave pyrrolo[1,2-a]isoquinolines without bridgehead oxidation. These results may have some significance for the origins of the bridgehead hydroxy natural products jenamidine B1/B2, clazamycin A/B and legonmycin A/B. The precursor cyclic aldimine for the synthesis of the indolizino[8,7-b]indoles gave dimeric indolizino[8,7-b]indoles, whereas the corresponding cyclic ketimines behaved as expected and gave the indolizino[8,7-b]indole core after reaction with cyclopropenones.
- Jamshaid, Faisal,Kondakal, Vishnu V.R.,Newman, C. Declan,Dobson, Rhianne,Jo?o, Heidi,Rice, Craig R.,Mwansa, Joseph M.,Thapa, Bimod,Hemming, Karl
-
-
Read Online
- GENERAL SYNTHESIS OF CYCLOPROPENONES AND THEIR ACETALS
-
Metalated cyclopropenone acetals 5 react with a variety of electrophiles, including alkyl halides, carbonyl compounds, vinyl iodides, vinyl triflates, and aryl iodides, to give substituted cyclopropenone acetals in high yield.Hydrolysis of the acetal unde
- Isaka, Masahiko,Ejiri, Satoshi,Nakamura, Eiichi
-
p. 2045 - 2058
(2007/10/02)
-
- Small Rings, 41. Oxirene: Intermediate or Transition State? Matrix Irradiation of Diazoketones
-
On irradiation of diazoketones - even of those which do not undergo a Wolff rearrangement under standard conditions - in an argon matrix at 10 K oxirenes (or acylcarbenes) cannot be detected directly.
- Maier, Guenther,Reisenauer, Hans Peter,Sayrac, Tugmac
-
p. 2192 - 2201
(2007/10/02)
-