Stereoselectivities of Diels-Alder cycloadditions of π-facially nonequivalent dienes to MTAD, PTAD, and N-methylmaleimide: A theoretical study

✍ Scribed by Alan.P. Marchand; Bishwajit Ganguly; Rajesh Shukla

• Book ID: 104208510
• Publisher: Elsevier Science
• Year: 1998
• Tongue: French
• Weight: 452 KB
• Volume: 54
• Category: Article
• ISSN: 0040-4020
• DOI: 10.1016/s0040-4020(98)00164-1

✦ Synopsis

hexachloro-1 a,4a,4aa,8aJ~-tetrahydro-1,4-methanonaphthalene (1) and 1,2,3,4,9,9hexachloro-let,4et,6,7-tetrahydro-1,4-methanonaphthalene (2) undergo n-facially diastereoselective Diels-Aider reactions with 4-methyl-and 4-phenyl-1,2,4-triazoline-3,5-dione [MTAD and PTAD, respectively] and with N-methyimaleimide (NMM). In contrast with the results of AM 1 calculations, those obtained via ab initio calculations performed at the HF/3-21G* level of theory predict that the computed Diels-Alder transition states are synchronous in all cases studied. Furthermore, these computational results account quantitatively for: (i) the observed n-facial selectivities of the various Diels-Alder reactions studied, (ii) the observed relative lack of dienophilic reactivity of NMM vis-~-vis MTAD and PTAD, and (ii) the observed enhanced diene reactivity of 1 vs. 2 in the reactions studied.