Asymmetric induction in Diels–Alder reactions of α-alkoxyorthoquinodimethanes

1989 ◽  
Vol 67 (6) ◽  
pp. 1010-1014 ◽  
Author(s):  
James L. Charlton ◽  
Guy L. Plourde ◽  
Glenn H. Penner
Keyword(s):  
Molecular Orbital ◽  
Geometry Optimization ◽  
Diels Alder ◽  
Asymmetric Induction ◽  
Molecular Orbital Calculations ◽  
Cycloaddition Reactions ◽  
Vinyl Ethers ◽  
The Face ◽  
Face Selectivity ◽  
Alkoxy Groups

It has been shown that dienophiles cycloadd selectively to one face of o-quinodimethanes (o-QDMs) bearing chiral α-alkoxy groups. The face selectivity (diastereoselectivity) increases for the series of chiral groups -OCH(Ph)CH3, -OCH(Ph)CH(CH3)2, and -OCH(Ph)C(CH3)3. A similar effect on the face selectivity of the Diels–Alder reactions of chiral alkoxy vinyl ethers for the same series of chiral groups has been noted previously by others. A mechanism has been proposed to explain the face selectivity in the cycloaddition reactions of the alkoxy o-QDMs. Abinitio molecular orbital calculations with geometry optimization on vinyl 1-phenylethyl ether to determine its lowest energy conformations support the proposed mechanism. The absolute stereochemistries of the o-QDM cycloadducts have been determined to verify the predictions of the model. Keywords: o-quinodimethanes, asymmetric, Diels–Alder, cycloaddition.

Molecular orbital structures of sulfones

1982 ◽  
Vol 60 (6) ◽  
pp. 730-734 ◽  
Author(s):  
Russell J. Boyd ◽  
Jeffrey P. Szabo
Keyword(s):  
Crystal Structure ◽  
Gas Phase ◽  
Molecular Orbital ◽  
Geometry Optimization ◽  
Membered Ring ◽  
Molecular Orbital Calculations ◽  
Bond Lengths ◽  
Comparison With Experiment ◽  
The Difference

Abinitio molecular orbital calculations are reported for several cyclic and acyclic sulfones. The geometries of XSO2Y, where X, Y = H, F, or CH3 are optimized at the STO-3G* level. Similar calculations are reported for the smallest cyclic sulfone, thiirane-1,1 -dioxide, as well as the corresponding sulfoxide, thiirane-1-oxide, and the parent sulfide, thiirane. Where comparison with experiment is possible, the agreement is satisfactory. In order to consider the possibility of substantial differences between axial and equatorial S—O bonds in the gas phase, as observed in the crystal structure of 5H,8H-dibenzo[d,f][1,2]-dithiocin-1,1-dioxide, STO-3G* calculations are reported for a six-membered ring, thiane-1,1-dioxide, and a model eight-membered ring. Limited geometry optimization of the axial and equatorial S—O bonds in the chair conformations of the six- and eight-membered rings leads to bond lengths of 1.46 Å with the difference being less than 0.01 Å.

Synthesis of functionalized hexahydro-, octahydro-, and decahydro-1H-phenalenes via Diels–Alder reactions of 1-methylene-4a-methoxycarbonyl-1,2,3,4,4a,5,6,7-octahydronaphthalene and related dienes

1993 ◽  
Vol 71 (9) ◽  
pp. 1463-1483 ◽  
Author(s):  
Edward Piers ◽  
Richard W. Friesen ◽  
Paul Kao ◽  
Steven J. Rettig ◽  
James Trotter
Keyword(s):  
Maleic Anhydride ◽  
Transition State ◽  
Methyl Acrylate ◽  
Diels Alder ◽  
Cycloaddition Reactions ◽  
Methoxycarbonyl Group ◽  
The Face ◽  
Group Reaction ◽  
Bicyclic Dienes

The results of a study of Diels–Alder reactions of the bicyclic dienes 6–8 with a variety of dienophiles are reported. Although 6 and 7 undergo cycloaddition reactions smoothly and efficiently, thermal Diels–Alder reactions of 8 are generally sluggish or, under the conditions investigated, do not proceed at all. Additions of tetracyanoethylene (TCNE) to 6–8 are highly face-selective, with preferential attack of the dienophile on the side of the dienes opposite to the angular methoxycarbonyl group. Reaction of 7 with maleic anhydride (MAN) is completely face-selective and proceeds preferentially via an endo transition state. Diels–Alder reactions of 6 and 7 with methyl acrylate (MAC) and nitroethylene (NE) are entirely regioselective, but the face-selectivities, which vary from ~2:1 to ~3:1, are rather low. The use of this chemistry as a method for the synthesis of functionalized, stereochemically defined, perhydro-1H-phenalenes is demonstrated.

Diastereoselectivity and asymmetric induction in the Diels–Alder reaction of o-quinodimethanes

1986 ◽  
Vol 64 (4) ◽  
pp. 720-725 ◽  
Author(s):  
James L. Charlton
Keyword(s):  
Maleic Anhydride ◽  
Methyl Acrylate ◽  
Dimethyl Fumarate ◽  
Alder Reaction ◽  
Diels Alder ◽  
Asymmetric Induction ◽  
Diels Alder Reaction ◽  
The Absolute ◽  
Alkoxy Groups

The extent of asymmetric induction in the bimolecular Diels–Alder reactions of chiral o-quinodimethanes with dimethyl fumarate, methyl acrylate, and maleic anhydride has been studied. o-Quinodimethanes with chiral α-alkoxy groups were prepared from 1-alkoxy-1,3-dihydrobenzo[c]thiophene-2,2-dioxides 4a–f or 1-alkoxy-3-phenyl-1,3-dihydrobenzo[c]thiophene-2,2-dioxides 4g–h by thermolysis. These alkoxybenzosulfones were prepared from the corresponding hydroxybenzosulfones 8 and 1-phenylethanol, 2-phenyl-1-propanol, 4-phenyl-2-butanol, 1-phenyl-2-propanol, 3,3-dimethyl-2-butanol, or 1-cyclo-hexylethanol. The 1-phenylethoxy substituent yielded the largest asymmetric induction. The absolute configurations of the major cycloadducts of methyl acrylate with the o-quinodimethanes generated from 1-(R- 1-phenylethoxy)- and 1-(S-1-phenylethoxy)-1,3-dihydrobenzo[c]thiophene-2,2-dioxides 4i and 4j have been determined to be 1S,2S-1-(R-1-phenylethoxy)- and 1R,2R-1-(S-1-phenylethoxy)-2-carbomethoxy-1,2,3,4-tetrahydronaphthalene 11i and 11j, respectively. The proposition that a chiral alkoxy substituent can block one face of the o-quinodimethane towards addition of a dienophile is discussed.

Effect of allylic substituents on the face selectivity of Diels-Alder reactions of semicyclic dienes

1990 ◽  
Vol 112 (23) ◽  
pp. 8472-8478 ◽  
Author(s):  
S. C. Datta ◽  
R. W. Franck ◽  
R. Tripathy ◽  
G. J. Quigley ◽  
L. Huang ◽  
...  
Keyword(s):  
Diels Alder ◽  
The Face ◽  
Face Selectivity

The face selectivity directed by an allylic group of a diene in the diels-alder reaction is reversed from that of a dienophile

1985 ◽  
Vol 26 (27) ◽  
pp. 3187-3190 ◽  
Author(s):  
Richard W. Franck ◽  
S. Argade ◽  
C.S. Subramaniam ◽  
Denise M. Frechet
Keyword(s):  
Alder Reaction ◽  
Diels Alder ◽  
Diels Alder Reaction ◽  
The Face ◽  
Face Selectivity

ChemInform Abstract: Effect of Allylic Substituents on the Face Selectivity of Diels-Alder Reactions of Semicyclic Dienes.

ChemInform ◽  
2010 ◽  
Vol 22 (6) ◽  
pp. no-no
Author(s):  
S. C. DATTA ◽  
R. W. FRANCK ◽  
R. TRIPATHY ◽  
G. J. QUIGLEY ◽  
L. HUANG ◽  
...  
Keyword(s):  
Diels Alder ◽  
The Face ◽  
Face Selectivity
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