Highly diastereoselective hetero-Diels–Alder reaction of buta-1,3-diene with N-glyoxyloyl-(2R)-bornane-10,2-sultam: an efficient synthesis of homochiral (S)-3-[2-{(methylsulfonyl)oxy}ethoxy]-4-(triphenylmethoxy)-1-butanol methanesulfonate
摘要:
The influence of Lewis acid on the diastereo selectivity of [4+2] cycloaddition of buta-1,3-diene to N-glyoxyloyl-(2R)-bornane-10,2-sultam was investigated and high levels of asymmetric induction were achieved. (S)-3-[2- (Methylsulfonyl)oxy}ethoxyl-4-(triphenylmethoxy)-1-butanol methanesulfonate were synthesized in 15% overall yield, applying as a crucial step the above-mentioned [4+2] cycloaddition catalyzed by ZnBr2. (C) 2003 Elsevier Science Ltd. All rights reserved.
Stereochemistry of the Diels–Alder reaction at high pressure: diastereo- and enantioselective [4+2]cycloaddition of buta-1,3-diene to glyoxylic acid derivatives catalysed by (salen) chromium(III) complexes
High-pressure [4+2]cycloadditions of buta-1,3-diene 1 to chiral 2a–c and achiral 7a–c glyoxylates, in the presence of (salen) chromium(III) complexes 5 and 6, were studied. The influence of such chiral Lewis acids on diastereoselectivity or enantioselectivity of the cycloaddition was investigated; a moderate asymmetricinduction for both diastereo- and enantioselective variants of the cycloaddition
<b>Diastereoselective Reaction of Buta-1,3-diene with Chiral Derivatives of Glyoxylic Acid: Effective Route to Optically Pure 2-Substituted 3,6-Dihydro-2</b>
<b><i>H</i></b>
<b>-pyrans</b>
The influence of Lewis acids on the diastereoselectivity of [4+2] cycloaddition of buta-1,3-diene (4) to N-glyoxyloyl-(2R)-bornane-10,2-sultam (6a) and (R)-8-phenylmenthyl glyoxylate (6b) was investigated and found to have high levels of asymmetric induction. The highest asymmetric induction (ca. 100% de) was obtained for the reaction of 4 with 6b carried out in toluene and in the presence of chelating