139617-38-2Relevant academic research and scientific papers
The synthesis of (+)-preussin and related pyrrolidinols by diastereoselective Paterno-Buechi reactions of chiral 2-substituted 2,3-dihydropyrroles
Bach, Thorsten,Brummerhop, Harm,Harms, Klaus
, p. 3838 - 3848 (2007/10/03)
The N-alkoxycarbonyl substituted 2,3-dihydropyrroles 3 and 8 are converted to 2-benzyl-3-pyrrolidinols by the Paterno - Buechi reaction followed by hydrogenolysis. Since the addition of the photoexcited benzaldehyde at the unsaturated heterocycle proceeds in a syn fashion, the benzyl group at C-2 and the hydroxy group at C-3 of the product are cis oriented. The simple and facial diastereoselectivities of the Paterno -Buechi reaction were studied more closely and the relative configuration of the products was elucidated. The thermodynamically less stable endo product is formed as a result of simple diastereo-selection. The face differentiation in 2-substituted 2,3-dihydropyrroles is presumably due to the nonplanarity of these heterocycles, which forces attack of the carbonyl group on the face with the existing substituent. All-cis-pyrrolidinols are consequently formed after hydrogenolysis. Following this route, a total synthesis of the pyrrolidinol alkaloid (+)-preussin (1) was conducted, which yielded the target compound in a total yield of 11% over nine steps starting from L-pyroglutaminol (11).
