Studies on the synthesis of the decahydro-as-indacene ring system of (-)-spinosyn A via transannular Diels-Alder reactions of substituted (E,E,E)-cyclododeca-1,6,8-trienes

2000 ◽  
Vol 78 (6) ◽  
pp. 757-771 ◽  
Author(s):  
Scott A Frank ◽  
Andrea B Works ◽  
William R Roush
Keyword(s):  
Transition State ◽  
Alder Reaction ◽  
Ring System ◽  
Diels Alder ◽  
Tandem Reactions ◽  
Ring Contraction ◽  
Diels Alder Reaction ◽  
Key Features ◽  
Stereoselective Syntheses

Stereoselective syntheses of decahydro-as-indacenes 31 and 54 are reported. The key features of our syntheses of 31 and 54 are the tandem Ireland-Claisen ring contraction of lactones 29 and 38 followed by the transannular Diels-Alder cyclization of cyclododecatrienes 30 and 35. Transition state modeling of both the transannular Diels-Alder reaction and the Ireland-Claisen ring contraction using PCModel is also described.Key words: transannular Diels-Alder reactions, tandem reactions, Claisen ring contraction, Spinosyn A, synthetic study.

scholarly journals Crystal structures and conformations of two Diels–Alder adduct derivatives: 1,8-bis(thiophen-2-yl)-14-oxatetracyclo[6.5.1.02,7.09,13]tetradeca-2(7),3,5-trien-10-one and 1,8-diphenyl-14-oxatetracyclo[6.5.1.02,7.09,13] tetradeca-2,4,6-trien-10-one

2015 ◽  
Vol 71 (2) ◽  
pp. 213-216
Author(s):  
S. Gopinath ◽  
P. Narayanan ◽  
K. Sethusankar ◽  
Meganathan Nandakumar ◽  
Arasambattu K. Mohanakrishnan
Keyword(s):  
Crystal Packing ◽  
Rotation Axis ◽  
Alder Reaction ◽  
Ring System ◽  
Diels Alder ◽  
Compound I ◽  
Diels Alder Reaction ◽  
Phenyl Rings ◽  
Axis Parallel ◽  
Alder Adduct

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).

Ab initio Cs transition state for the Diels-Alder reaction of acetylene and butadiene

1990 ◽  
Vol 55 (12) ◽  
pp. 3804-3807 ◽  
Author(s):  
James M. Coxon ◽  
Stephen T. Grice ◽  
Robert G. A. R. Maclagan ◽  
D. Quentin McDonald
Keyword(s):  
Transition State ◽  
Ab Initio ◽  
Alder Reaction ◽  
Diels Alder ◽  
Diels Alder Reaction

ChemInform Abstract: First Evidence of a Chair-Boat-Boat Transition State in the Transannular Diels-Alder Reaction.

ChemInform ◽  
2010 ◽  
Vol 25 (38) ◽  
pp. no-no
Author(s):  
Y. L. DORY ◽  
C. OUELLET ◽  
S. BERTHIAUME ◽  
A. FAVRE ◽  
P. DESLONGCHAMPS
Keyword(s):  
Transition State ◽  
Alder Reaction ◽  
Diels Alder ◽  
Diels Alder Reaction
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