21. Rationale for the Endo Selectivity of the 1, 3-Dipolar Cycloaddition Reaction with a Lewis Acid 22. Dipolar theism holds that in each pair, both of the characteristics contain some element of good.23. E . g . with alkynes they generate pyrazoles in a 1, 3-dipolar cycloaddition. 24. The coupling is given by g = E \ cdot d ( for electric dipolar coupling ). 25. He introduced the Jeener-Broekaert sequence for creating observable quantities of dipolar order in solids. 26. Heteroatom-containing dipolarophiles such as carbonyls and imines can also undergo 1, 3-dipolar cycloaddition. 27. 1, 3-dipolar cycloaddition reactions between carbonyl ylide dipoles and alkenyl dipolarophiles can generate diastereomeric products. 28. Two common mechanisms by which electrons and nuclei interact are the Fermi contact interaction and by dipolar interaction. 29. They apply not only for a perfect dipole field, but also for fields that are approximately dipolar . 30. The last two nuclei are quadrupolar nuclei whereas the preceding two nuclei ( and ) are dipolar ones.
