Pure enantiomers from retro-diels-alder processes

Synthesis and Cycloaddition Reactions of 1-(Arylthio)-1,3-dienes. A Combined Experimental and Theoretical Study of Bicyclic Adducts Structures

“…The control of the overall shape of taylor-made molecules has become lately a real challenge to organic chemists since this parameter is the key assett in supramolecular chemistry. It has, for instance, been shown that advantage may be taken from the conformational rigidity imposed by a chiral tricyclic system to induce asymmetry through an efficient Diels−retro Diels sequence of reactions. We have thus tried to determine the exact conformation of these adducts from available experimental data on the one hand and quantum mechanical calculations on the other.…”

Synthetic Approaches to Enantiomerically Enriched 4-Hydroxycyclohex-2-en-1-one - A Key Chiral Building Block in Complex Natural Product Synthesis

“…In this case, the trans-configured vic-diol of 2 was selectively protected, as opposed to the cis-diol in Danishefsky's route. Thus, when quinic acid (2) was exposed to 1,1,2,2-tetramethoxycyclohexane (10) under acidic conditions, the trans-diol protected product 11 was formed in 57% yield (Scheme 2). The sequence then proceeded in a similar fashion to that shown in Scheme 1 to furnish enone (R)-1 in a total of six steps and an overall yield of 18% from (-)-quinic acid (2).…”

“…Winterfeldt and co-workers utilised a Diels-Alder/reduction/retro-Diels-Alder sequence to synthesise either (S)-1 or (R)-1. 9 Using diene 30 10 as the chiral template, high-pressure (6.5 kbar) cycloaddition with para-benzoquinone furnished Diels-Alder adduct 32 (Scheme 7). Selective hydrogenation and reduction led to alcohol 33 in a diastereo-and regioselective manner.…”

Enantiomerically pure cyclopentadienes

“…Their optical purity was proven by shift reagent measurements97 and their absolute configuration was proven by a stereoselective synthesis from lactate. 97 At this stage we were convinced that cyclopentadienes like 62 could be expected to provide cycloaddition products with a very high degree of selectivity. Additionally there remained no doubt that adducts generated from nonsymmetric dienophiles would give rise to subsequent reaction products with remarkable stereoselectivity and regioselectivity.…”