X-Y-ZH Systems as potential 1,3-dipoles

Potentially Biomimetic Total Synthesis and Relative Stereochemical Assignment of (±)‐Gracilamine

“…At the outset, this was a challenging task as only a few reports regarding the [3+2] cycloaddition of non-polar olefins and azomethine ylides exist. [14] It is noteworthy that attempts to use Lewis acids, such as silver and copper salts, to promote the intramolecular [3+2] cycloaddition failed to give any desired products under typical reaction conditions.…”

Three‐component 1,3‐dipolar cycloaddition reactions in synthesis of spiro[pyrrolidine‐2,3′‐oxindoline] derivatives

“…Assuming that the kinetically favored dipole has the configuration 4, we believe that 7a arises via an endo-transition state. The formation of 7a indicates that the reduced steric hindrance at the singly substituted azomethine ylide terminus outweighs the more favorable orbital interaction between the dipole (HOMO) of 4a and dipolarophile (LUMO) of 6a usually observed in these reactions [23]. The regiochemistry of 7a was apparent from the multiplicity of the 4-H signal in its 1 H NMR spectrum.…”

Silver: Inorganic & Coordination ChemistryBased in part on the article Silver: Inorganic & Coordination Chemistry by W. Ewen Smith which appeared in the Encyclopedia of Inorganic Chemistry, First Edition .

“…38 For SILVER: INORGANIC & COORDINATION CHEMISTRY 7 example, AgOAc catalyzes the cycloaddition of (1), an arylidene imine of an α-amino acid ester, to dipolarophile (2), to give the proline derivative (3) in 71% yield. 39 A catalytic amount of AgBF 4 promotes the rearrangement of housane (4) to the diastereomeric cyclopentenes (5) (endo-CD 3 group migration, 86% yield) and (6) The complex [HB{3,5-(CF 3 ) 2 pz} 3 ]Ag(THF) (7) has been employed in the silver-catalyzed activation of carbon-halogen bonds through a carbene insertion process that occurs at room temperature, resulting in formation of a new sp 3 The remarkable affinity of the silver ion for halides can be conveniently applied to accelerate the chiral palladium-catalyzed Heck reaction and other reactions. 42 Enantioselectivity of these reactions is generally increased by addition of silver salts, and hence silver(I) compounds in combination with chiral ligands hold much promise as chiral Lewis acid catalysts for asymmetric synthesis.…”