2‐Methoxy‐Δ³‐1,3,4‐oxadiazoline, a Multipurpose Precursor for the Generation of a Carbene, an Ylide, or a Diazo Compound

Abstract

In the course of our investigation of the intermolecular reactions of foiled carbenes of the norborn-2-en-7-ylidene type, we have investigated the decomposition of methoxyoxadiazoline 1 in alcohols. Most of the reactions performed lead to products with an anti configuration confirming the participation of the double bond to the stabilization of the transition states. The thermal behavior of spirooxadiazoline 1 is quite different from the behavior of the parent 2-methoxy-2,5,5-trimethyl-∆ 3 -1,3,4-oxadiazoline. Photolysis of 1 leads to the carbene after prior formation of the diazo compound whereas thermolysis cleanly generates an extremely unstable carbonyl ylide 4 that immediately decomposes to the stabilizednucleophilic carbene 5 and methyl acetate without genera-

Probing the Nature and Extent of Stabilization within Foiled Carbenes: Homoallylic Participation by a Neighboring Cyclopropane Ring

“…Subsequent methanolysis of 13 gives 14 . A similar reaction sequence was observed for the oxadiazoline precursor of 2 . In contrast, the distal ylide intermediate formed from 6b (not shown) might be destabilized by electron donation from the three-membered ring because of the aforementioned endo , anti relationship.…”

Straightforward Synthesis of Ethers: Metal‐Free Reductive Coupling of Tosylhydrazones with Alcohols or Phenols

“…The combination of the diazo compound generated from the tosylhydrazone [10] with a hydroxylic compound would result in the formation of an ether, through an insertion reaction of the incipient carbene into the OÀH bond. [11] Although many OÀH insertion processes with phenols have been reported before, most of the examples involve diazo compounds stabilized by electron-withdrawing groups such as diazo ketones or diazo esters. [12,13] Moreover, the majority of the transformations are acid- [14] or transitionmetal-catalyzed reactions, [15] as well as photochemical transformations.…”

Conformations and Reactions of Bicyclo[3.2.1]oct-6-en-8-ylidene

“…However, their use in aprotic solvents is limited by their poor solubility in these media. 2,2-Dialkyl-5-methyl-5-methoxyoxadiazolines are precursors of carbenes, accessible by photodecomposition, by thermolysis, or by vacuum flash pyrolysis . However, the detailed mechanism of their decay to carbene species is complex .…”

“…2,2-Dialkyl-5-methyl-5-methoxyoxadiazolines are precursors of carbenes, accessible by photodecomposition, by thermolysis, or by vacuum flash pyrolysis . However, the detailed mechanism of their decay to carbene species is complex . These oxadiazolines are quite soluble in common organic solvents and stable at room temperature.…”