Diastereoselective Diels-Alder Reaction Research Articles

Highly diastereoselective Diels-Alder reactions with (R)-ethoxy p-tolyl vinyl sulfonium tetrafluoroborate

p-Tolyl vinyl sulfoxide has been efficiently activated for Diels-Alder reactions by transformation into a sulfonium salt 3a or by addition of TMSOTf. Very high diastereomeric excesses have been achieved (>98%) at −20°C in many cases. Best results have been obtained with cyclopentadiene, furan and 2,3-dimethyl-1,3-butadiene. In this way enantiomerically pure oxanorbornenone 19a has been prepared. The reaction mechanism is briefly discussed.

A New Enantioselective Approach to the Bicyclo[4.4.0]decane and Bicyclo[4.3.0]nonane Systems

Abstract Highly diastereoselective routes to cis-fused bicyclo[4.4.0]decane-2,10-diones and bicyclo[4.3.0]nonane-2,9-diones from 5-trimethylsilyl-2-cyclohexen-1-one (1a) and its 3-methyl derivative were established by utilizing an annulation with ω-(alkoxycarbonyl)alkylzinc reagents. Bicyclo[4.4.0]decane-2,8-dione was obtained diastereoselectively by the double Michael reaction of 1a with dienol silyl ether. The diastereoselective Diels–Alder reaction of 1a with cyclopentadiene gave an endo adduct, which can be regarded as a new chiral cyclohexenone synthon, with a high optical purity.

Highly diastereoselective diels-alder reaction of optically active 2- p-tolylsulphinyl-2-cycloalkenones with cyclopentadiene

The Diels-Alder reaction of (S)-2- p-tolylsulphinyl-2-cyclopentenone (and 2-cyclohexenone) with cyclopentadiene, catalized by AlCl 3 and AlEtCl 2, occurs at room temperature with complete facial diastereoselectivity, but with moderate endo-exo selectivity.

Diastereoselective Diels–Alder Reaction on Carbohydrate Matrices

A complex or carbohydrate-bound acrylate and chlorotitanate determines the configuration of the Diels–Alder product of acrylate and cyclopentadiene. That (R)-2 and (S)-2 are formed in the ratio 93 : 7 can be rationalized in terms of the structure 1 for this complex.

ChemInform Abstract: The First Efficient Asymmetric Synthesis of 7‐Oxabicyclo[2.2.1]hept‐5‐ene‐2‐carboxylate Derivatives.

AbstractDie aus dem (+)‐Menthylester (I) und 2‐Mercaptopyridin (II)erhaltenen optisch reinen Sulfoxide (IIIa) und (IIIb) ergeben mit Furan unter hoher Diastereoselektivität die Cycloaddukte (V) und (VI) bzw. (VII) und (VIII), von denen die rohen endo‐Cycloaddukte (V) und (VII) in optisch aktive Sulfenylalkohole (IX) und (XI) umgewandelt werden können.

Diastereoselective diels-alder reactions of optically-active vinyl sulphoxides

The Diels-Alder reaction of an optically active vinyl sulphoxide containing a second electron withdrawing group with cyclopentadiene gave separable diastereomers. The effect of Lewis acid catalysis on the reaction was studied. Reaction of an acetylenic anion with menthyl p-toluene sulphinate gave an anomalous product.

Highly diastereoselective Diels-Alder reaction of optically active ethyl 2-p-tolylsulfinylmethylenepropionate with cyclopentadiene

Stereochemistry of the Diels-Alder reaction of ethyl Z- and E-2-ptolylsulfinylmethylenepropionate with cyclopentadiene has been studied. The high diastereoselectivity was observed especially in the case of exo-cycloaddition.