Temperature andPara-Substituent Effects on the Face Selectivity of 1,3-Dipolar Cycloaddition Reactions of Benzonitrile Oxides with 5-Substituted Adamantane-2-thiones,N-Benzyladamantyl-2-imines, and 2-Methyleneadamantanes

1999 ◽  
Vol 64 (4) ◽  
pp. 1099-1107 ◽  
Author(s):  
Tzong-Liang Tsai ◽  
Wei-Cheng Chen ◽  
Chin-Hui Yu ◽  
W. J. le Noble ◽  
Wen-Sheng Chung
Keyword(s):  
Substituent Effects ◽  
Dipolar Cycloaddition ◽  
Cycloaddition Reactions ◽  
The Face ◽  
Face Selectivity

Nitrones and oxaziridines. XXI. Electronic substituent effects in nitrone cycloadditions to highly polarized alkenes

1978 ◽  
Vol 31 (10) ◽  
pp. 2239 ◽  
Author(s):  
DSC Black ◽  
RF Crozier ◽  
ID Rae
Keyword(s):  
Substituent Effects ◽  
Dipolar Cycloaddition ◽  
Cycloaddition Reactions ◽  
Zwitterionic Intermediate

1,3-Dipolar cycloaddition reactions of nitrones-particularly N-(2'- pyridylmethylene)aniline N-oxide-with arylmethylene cyanoacetates exclusively yield 4,4-disubstituted isoxazolidines, identifiable by 1H n.m.r, spectroscopy and isolable in some cases. Comparative kinetic experiments provide evidence for at least non-synchronous addition via a dipolar intermediate or possibly even two-step addition via a discrete zwitterionic intermediate.

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.

Face Selectivity in the 1,3-Dipolar Cycloaddition Reactions of Benzonitrile Oxide with 5-Substituted Adamantane-2-thiones and 2-Methyleneadamantanes†

1997 ◽  
Vol 62 (14) ◽  
pp. 4672-4676 ◽  
Author(s):  
Wen-Sheng Chung ◽  
Tzong-Liang Tsai ◽  
Chia-Chin Ho ◽  
M. Y. N. Chiang ◽  
W. J. le Noble
Keyword(s):  
Dipolar Cycloaddition ◽  
Cycloaddition Reactions ◽  
Face Selectivity

Multicomponent 1,3-Dipolar Cycloaddition Reactions in the Construction of Hybrid Spiroheterocycles

2013 ◽  
Vol 17 (18) ◽  
pp. 1929-1956 ◽  
Author(s):  
Natarajan Arumugam ◽  
Raju Kumar ◽  
Abdulrahman Almansour ◽  
Subbu Perumal
Keyword(s):  
Dipolar Cycloaddition ◽  
Cycloaddition Reactions

Chemistry of Unsymmetrical C1-Substituted Oxabenzonorbornadienes

2021 ◽  
Vol 17 ◽  
Author(s):  
Austin Pounder ◽  
Angel Ho ◽  
Matthew Macleod ◽  
William Tam
Keyword(s):  
Transition Metal ◽  
Metal Complexes ◽  
Transition Metal Complexes ◽  
Substituent Effects ◽  
Face Selectivity ◽  
Transition Metal Catalyzed ◽  
Catalyzed Reactions ◽  
Metal Catalyzed ◽  
Synthetic Intermediate

: Oxabenzonorbornadiene (OBD) is a useful synthetic intermediate which can be readily activated by transition metal complexes with great face selectivity due to its dual-faced nature and intrinsic angle strain on the alkene. To date, the understanding of transition-metal catalyzed reactions of OBD itself has burgeoned; however, this has not been the case for unsymmetrical OBDs. Throughout the development of these reactions, the nature of C1-substituent has proven to have a profound effect on both the reactivity and selectivity of the outcome of the reaction. Upon substitution, different modes of reactivity arise, contributing to the possibility of multiple stereo-, regio-, and in extreme cases, constitutional isomers which can provide unique means of constructing a variety of synthetically useful cyclic frameworks. To maximize selectivity, an understanding of bridgehead substituent effects is crucial. To that end, this review outlines hitherto reported examples of bridgehead substituent effects on the chemistry of unsymmetrical C1-substituted OBDs.

Sign in / Sign up

Export Citation Format

Share Document