scholarly journals HIGHLY SELECTIVE INTRODUCTION OF CONJUGATED DIENES TO GOOD DIENOPHILES, α,β-UNSATURATED CARBONYL COMPOUNDS ANDp-QUINONES, WITHOUT FORMATION OF DIELS–ALDER ADDUCT

1983 ◽  
Vol 12 (11) ◽  
pp. 1683-1686 ◽  
Author(s):  
Yoshinori Naruta ◽  
Naoshi Nagai ◽  
Yoshihiro Arita ◽  
Kazuhiro Maruyama
1996 ◽  
Vol 74 (11) ◽  
pp. 2048-2063 ◽  
Author(s):  
Edward Piers ◽  
Richard D. Tillyer

Treatment (dry tetrahydrofuran, reflux) of the α,β-alkynic aldehydes 26–28 and ketones 29–36 with Me3SnSnMe3 in the presence of a catalytic amount of (Ph3P)4Pd provides fair to excellent yields of the corresponding (Z)-β-trimethylstannyl α,β-alkenic aldehydes 41–43 and ketones 44–51. The carbonyl compounds 41–51, upon reaction with methylenetriphenylphosphorane under suitable conditions, are smoothly converted into the (Z)-4-trimethylstannyl-1,3-butadienes 61–71, respectively. Treatment of the aldehyde 41 with the anion of trimethyl phosphonoacetate and the aldehyde 42 with the anion of the phosphonoacetate 73 produces excellent yields of the 5-trimethylstannyl-2,4-heptadienoates 72 and 74, respectively. The synthetic potential of (Z)-4-trimethylstannyl-1,3-butadienes is illustrated by the conversion of 62 into the functionalized, stereodefined conjugated dienes 76 and 78 and by transformation of 87 into the structurally novel diene 84. Diels–Alder reactions of 84 with tetracyanoethylene and dimethyl acetylenedicarboxylate provide the spiro[3.5]nonane derivatives 88 and 89, respectively. Key words: Diels–Alder cycloaddition, organocopper(I), transmetallation, alkylidenecyclobutane, (E)-4-lithio-1,3-butadienes, spiro[3.5]nonane.


2014 ◽  
Vol 10 (6) ◽  
pp. 951-960
Author(s):  
Orazio Attanasi ◽  
Luca Bianchi ◽  
Maurizio D’Auria ◽  
Gianfranco Favi ◽  
Fabio Mantellini ◽  
...  

Author(s):  
S. Gopinath ◽  
P. Narayanan ◽  
K. Sethusankar ◽  
Meganathan Nandakumar ◽  
Arasambattu K. Mohanakrishnan

The title compounds, C21H16O2S2(I) and C25H20O2(II), are products of a tandem `pincer' Diels–Alder reaction consisting of [2 + 2] cycloadditions between benzo[c]furan and cyclopentanone. Each comprises a fused tetracyclic ring system containing two five-membered rings (inenvelopeconformations with the O atom as the flap) and six-membered rings (inboatconformations). In addition, two thiophene rings in (I) and two phenyl rings in (II) are attached to the tetracyclic ring system. The cyclopentanone ring adopts atwistedconformation in (I) and anenvelopeconformation in (II). In (I), the thiophene rings are positionally disordered over two sets of sites, with occupancy ratios of 0.901 (2):0.099 (2) and 0.666 (2):0.334 (2). In (II), the oxygen atom of the cyclopentanone ring is rotationally disordered over two sites with an occupancy ratio of 0.579 (4):0.421 (4). The molecular structure of (I) is stabilized by an intramolecular C—H...O hydrogen bond, which generates anS(7) ring motif. In the crystal, the molecules are linkedviaweak C—H...O hydrogen bonds, which generateR22(16) ring motifs in (I) andC(8) chains in (II). In both structures, the crystal packing also features C—H...π interactions. The crystal studied of compound (I) was twinned by non-merohedry. The twin component is related by the twin law [−1 0 0 −0.101 1 −0.484 0 0 −1] operated by a twofold rotation axis parallel to thebaxis. The structure of (I) was refined with a twin scale factor of 0.275 (2).


1992 ◽  
Vol 45 (12) ◽  
pp. 2089 ◽  
Author(s):  
EL Ghisalberti ◽  
BW Skelton ◽  
AH White

The structure of the compound obtained on heating the naturally occurring clerodane furanoditerpene (1) had been formulated as (2) on the basis of spectroscopic studies. A single-crystal X-ray diffraction study on the dihydro derivative of (2) has confirmed this and provides support for the stereochemistry previously assigned to (1) on the basis of chemical evidence.


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