Δ3-1,3,4-Oxadiazolines.† Versatile sources of reactive intermediates

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

“…As a multipurpose precursor, oxadiazolines may decompose either to a ketone, a diazo compound, or a carbonyl ylide. [1] Whereas the chemistry of ketones and diazo compounds is well understood, carbonyl ylides remain fascinating species with properties that are extremely dependant on their substitution. [15] For example, ylides formally derived from the addition of an electrophilic carbene to a carbonyl group are convenient intermediates to undergo 1,3-dipolar cycloadditions to double bonds.…”

“…[1] Especially, 2-alkoxy-∆ 3 -1,3,4-oxadiazolines are very attractive since Warkentin has shown some 20 years ago that they are suitable for the generation of alkyl carbenes under photochemical conditions after prior formation of a diazoalkane. [2] Indeed, they have permitted numerous investigations.…”

The First Reaction of Dimethoxycarbene with an Imine Moiety

“…In the case of the nucleophilic dimethoxycarbene, the most extensively studied reactions with relevant practical applications (two-or multi-component reactions) are focused on the use of ketones [4] [9] or mixtures of acetylene dicarboxylate and an aldehyde [10] as substrates. Recently, DMC was shown to react smoothly with cycloaliphatic thioketones [11] 4 and dithiocarboxylates [12].…”

Thermolysis of Imidates: A New Method for the Generation of Carbonyl Ylides

“…-Carbonyl ylides are highly reactive intermediates of increasing interest, which are frequently applied for the purposes of organic chemistry [1] [2], particularly in natural product synthesis [3]. Several methods [4][5][6][7][8] for the generation of these reactive species from different classes of compounds enable the introduction of a wide variety of functionalities into the structure of the final product. In combination with high efficiency and selectivity of the reactions, this often makes carbonyl ylides the key intermediates in the design of synthetic strategies [3].…”

“…The known methods for the generation of carbonyl ylides 1 involve photochemical and thermal ring opening of substituted oxiranes 2 [4], thermal decomposition of substituted 1,3,4-oxadiazolines 3 [5], 1,3-elimination reactions of trimethylsilyl substituted chloromethyl ethers 4 [6], SmI 2 mediated generation of nonstabilized carbonyl ylides (1; R 3 , R 4 = R 1 , R 2 ) from α-iodomethyl trialkylsilyl ethers 5 [7], thermal decomposition of organomercury compounds 6 in the presence of carbonyl compounds [8], and decomposition of α-diazocarbonyl compounds 7, mostly with Rh or Cu complexes, in the presence of compounds which contain a C=O group in their structure [3] (Scheme 1). The latter method greatly advanced the application of carbonyl ylides to the synthesis of complex natural products.…”