From telluronium ylides

From telluronium ylides 4.7.3.1 Stabilized telluronium ylides... 

Thus, allyl telluronium ylides generated in situ from the corresponding telluronium salts in the presence of Li salts react with a,)3-unsaturated esters and amides to afford trans-2-vinyl-/rany-3-substituted cyclopropyl compounds in high yieds. 

The semi-stabilized telluronium ylides, generated in situ from the corresponding telluronium salts (156 R1 = CH=CHSiMe3, CH=CH2, CH=CHMe, CH=CHPh, Ph), have been reported to react with a,/(-unsaturated carbonyl compounds (157 R2 = Ph, OR, NR)) to afford 2-vmylcyclopropyl derivatives (158) with high... 

Telluronium ylides,118 derived from triorganotelluronium salts 63, react with aldehydes, ketones, and a,/3-unsaturated esters to give different products depending on the nature of the substituent at the a-carbon of the telluronium salt 63. In Scheme 31,121-123 examples of such transformations are given. 

The synthesis of aziridines from imines and sulfur ylides has been reviewed in previous editions of PHC and is a well-known reaction. A current study reveals that telluronium ylides add to a,p-unsaturated imines through a Michael addition-elimination to the olefin followed by a second equivalent of telluronium ylide addition to the imine, which subsequently eliminates to form aziridines 137 and 138 in a ratio of 13 1 <05JA12222>. 

We add an investigation of Chinese chemists to this section, although it is not related to carbenoid reagents that we have discussed above. Zhou et al. (1993) studied reactions of dimethyl diazomalonate and ethyl diazoacetate with carbonyl compounds mediated by diorganyl tellurides and catalytic amounts of cuprous iodide (8-69). Dibutyl telluride (8.155) yields the dimethyl l-arylethene-2,2-dicarboxylate 8.157 with 4-chlorobenzaldehyde in 95<7b yield at 100 °C. It is assumed that the reaction passes the telluronium ylide 8.156 as intermediate. If so, the process is clearly different from the carbenoid transformations discussed in this section. The originally diazo-substituted C-atom has nucleophilic character in 8.156 and is not electrophilic, as in 8.104. 

Di-, tri-, and tetra-substituted 2-azadienes (64) carrying electron-withdrawing groups have been synthesised by the aza-Wittig reaction. A one-pot synthesis of olefins from diorganyltelluride, diazo compounds, and carbonyl compounds in the presence of a Cu(I) catalyst is suggested to involve a Wittig-type reaction of an intermediate telluronium ylide. ... 

Tetraphenylcyclopentadienylides, as shown in the exanqile given, have, in particular, been made from diazotetraphenylcyclopentadiene. By this means pyridinium [60,102,134], phosphonium [52,104,105], arsonium [105,106,134,135], stibonium [107], bismuthonium [108], sulphonium [105,109,113,134], selenonium [114] and telluronium [115] ylides have been prepared. The method is improved by the presence of copper conpounds as catalysts and may then often be carried out in solution [105,134], Thermal decomposition of unsubstituted diazocyclopentadiene has not been used to provide cyclopentadien-ylides but sulphonium ylides have been made by photolytic decomposition in the presence of various sulphides [110,111]. 

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