Diastereoselective route to (2R,5S)- and (2S,5S)-2-methyl-1,6-dioxaspiro[4.5]decane, a pheromone component of the wasp Paravespula vulgaris
作者:Paulo H.G. Zarbin、Alfredo R.M. de Oliveira、Carlos E. Delay
DOI:10.1016/s0040-4039(03)01716-7
日期:2003.9
A diastereoselective approach to (2R,5S)- and (2S,5S)-2-methyl-1,6-dioxaspiro[4.5]decane 1 and 1a is described. The route starts with an alkylation reaction among the cyclopentanone N,N-dimethylhydrazone 6 and the chiral iodides (R)-3 or (S)-3, derived from the enantiomers of ethyl β-hydroxybutyrate, controlling the estereocenter at C-2 of the molecules. The alkylated products 7 and 7a were easily
The stereoselective synthesis of the (2R,5S)-2-methyl-5-hexanolide, a sex pheromone of Xylocopa hirutissima, has been achieved in 6 steps and 33% overall yield. The synthesis relies on an asymmetric N-acetyl thiazolidinethione aldol reaction to establish the C5 stereogenic centers. The remaining stereogenic center at C2 was set through a N-propionylprolinol-mediated asymmetric alkylation reaction.
The application relates to substituted 4-phenylpiperidines of the general formula and their salts, preferably their pharmaceutically acceptable salts, in which R
2
, R
3
, W and X have the meanings explained in the description, a process for their preparation and the use of these compounds as medicines, especially as renin inhibitors.
Studies toward the total synthesis of (+)-ptilomycalin A. Use of a tethered Biginelli condensation for the preparation of an advanced tricyclic intermediate
作者:Larry E. Overman、Michael H. Rabinowitz
DOI:10.1021/jo00064a007
日期:1993.6
An intramolecular ureidoaldehyde condensation, 16 + (R)-14 --> 19, is the key step in a seven-step preparation of the enantiopure spirotricycle 23, a potential intermediate for the enantioselective total synthesis of ptilomycalin A.