Chloro phenyl carbene

B. C-H Insertion Reaction with Chloro(phenyl)carbene. 292... 

Chloro(phenyl)carbene or carbenoid generated from benzal chloride reacts with potassium salts of benzylic, allylic, and other alkoxides to produce phenyl-substituted oxiranes 9 in high yields, as an approximately 1 1 mixture of cis... 

Table 2. Reaction of Chloro(Phenyl)Carbene with Alkoxides °...

Scheme 13 Ring expansion of chloro(phenyl)carbene (64).

Photolyses of 3-ch 1 oro-3-pheny 1 -3//-dia/irine (63) were carried out within CyDs and FAU zeolites to foster the ring expansion of the carbene intermediate, chloro(phenyl)carbene (64). However, benzaldehyde (PhCHO) was formed instead of products derived from l-chloro-l,2,4,6-cycloheptatetraene (65). Since CyD innermolecular products were also formed, control experiments in relevant solvents were performed. The true structure of the innermolecular product that was formed in alkaline buffer, and then observed via FAB MS and RP HPLC, has not yet been determined. The ability of the basic medium to preserve the innermolecular product and reduce the amount of PhCHO formed seems to indicate that the latter stems from the former, e.g., O-H insertion product 82. However, the exact mechanism of PhCHO formation within the CyD ICs could not be pinpointed. 

Chloro(phenyl)carbene adds to ring-substituted styrenes to give cyclopropanes 3 in very low yield together with (Z)-l,2-dichloro-l,2-diphenylethene. ... 

Enamines derived from cyclohexanone and and a-tetralones react with chloro-(phenyl)carbene [generated from dichloro(phenyl)methane and potassium tert-butoxide] to give either 1-chloro-l-phenyl-substituted cyclopropanes, or other products.The type of products formed depends on the structure of the amine moiety in the starting enamines (Table 7). 

Table 7. The Products of the Addition of Chloro(phenyl)carbene (from PhCHClj/f-BuOK) to Enamines...

Addition of chloro(phenyl)carbene, generated from diazirine, to alkenes is stereospecific, yet diethyl (Z)-but-2-enedioate isomerized partially to give a mixture of stereoisomeric cyclopropanes(for a more detailed discussion see Houben-Weyl, Vol. E19b, p995). 

The adducts of chloro(phenyl)carbene to ( )-but-2-enedinitrile and maleic anhydride have also been prepared. " ... 

Dichloro(phenyl)methyl](trimethyl)tin is more stable, and forms chloro(phenyl)carbene at 140-160"C only. This reaction carried out with 2,3-dimethylbut-2-ene afforded diene 13 via 1-chloro-l-phenylcyclopropane, which did not survive the reaction conditions. ... 

The process consists of the chlorination of dibromomethyl carbanion with trichlo-ro(phenyl)methane and fast protonation of the dichloromethyl(phenyl) carbanion formed, which does not dissociate into chloro(phenyl)carbene and chloride anion. Only in the case of alkenes of decreased nucleophilidty are small amounts of 1,1-dibromocyclopropanes formed. 

Full details have been given for the preparation of chloro(phenyl)carbene (3), from the corresponding diazirine, and for its subsequent trapping by /3-methylstyrene, leading to the cyclopropene (4) after dehydrochlorination. An excellent new catalyst for the synthesis of cyclopropanecarboxylates (5), from olefins and diazoesters, is the rhodium cluster compound, Rh6(CO)i6. In general, good yields of (5) are only obtained if a large excess of olefin is used, but other work... 

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