Cyclopropane ring opening nucleophilic

The addition of nucleophiles to cyclic fluoroolefins has been reviewed by Park et al. [2 ]. The reaction with alcohols proceeds by addition-elimination to yield the cyclic vinylic ether, as illustrated by tlie reaction of l,2-dichloro-3,3-di-fluorocyclopropene Further reaction results in cyclopropane ring opening at the bond opposite the difluoromethylene carbon to give preferentially the methyl and ortho esters of (Z)-3-chloro-2-fluoroacrylic acid and a small amount of dimethyl malonate [29] (equation 8). 

Internal cyclopropane ring-opening reactions have also been developed using hydroxyl-substituted cyclopropanes. A typical example of this strategy comes from the reaction of the polycylic alcohol 131, which reacts quantitatively with Hg(OAc)2 to yield the acetal 132 (Equation (45)).165 Carbonate moieties can also be used as internal nucleophiles as, for example, in the case of 133, which affords 134 in a 60% yield upon reaction with Hg(OCOCF3) (Equation (46)).166... 

Depending on the reaction conditions, the allylic cation can be trapped by the halide ion expelled during cyclopropane ring opening or by an external nucleophile. For example, 3,3-dibromotricyclo[4.1.1.0 ]octane (14) rearranged to give 15. ... 

Cyclopropylphosphine oxides (140) react with the sodium salts of amides, presumably via cyclopropane ring-opening and intramolecular olefination, to give dihydropyrrole derivatives in moderate to good yield. Vicarious nucleophilic substitution reactions of a variety of substituted nitrobenzene derivatives with the carbanion of chloromethyldiphenylphosphine oxide to give o-(141) and p-(142)-nitrobenzyldiphenylphosphine oxides have been investigated. ... 

Selective ring opening of cyclopropanes. Ring opening by nucleophiles of suitably activated cyclopropanes has gained importance during recent years. Sodium or potassium cyanide can be used for this purpose. An example is the conversion of 1 or 2 into 3, ant/-7-cyano-eni/o-5-bromobicyclo[2.2.1]heptane-2-one, by reaction with potassium cyanide in the presence of catalytic amounts of sodium methoxide (equation T). The intermediate 2 can be isolated in high yield by reaction of 1 with 1 equiv. of sodium hexamethyldisilazide (4, 407) in ether. ... 

A cycloisomerization cascade from alkynylcyclopropanecarboxylic acid derivatives to oxepinones and azepinones has been reported to involve nucleophilic addition followed by a cyclopropane ring opening, where both donor and acceptor groups are required as substituents of the cyclopropane ring (Scheme 133). ... 

Pyridine hydrochloride Nucleophilic cyclopropane ring opening... 

The allylic esters 189 and 191 conjugated with cyclopropane undergo regio-selective reactions without opening the cyclopropane ring. The soft carbon nucleophiles are introduced at the terminal carbon to give 190, and phenylation with phenylzinc chloride takes place on the cyclopropane ring to form 192[120]. 

The reactions of benzothiazinium salt 87d with nucleophiles such as PhSNa, PhSeNa, and KCl were examined (see Equation (24) and Table 13) <1997J(P1)309>. Treatment of 87d with PhSNa at 0°C for 2h provided vinyl cyclopropane 88d (82%) as the major product together with ring-opened product 90a (11%) (see entry 1). When the reaction was carried out with PhSeNa at —20 °C, and then warmed to room temperature, 90b was obtained in a higher yield (94%) with only trace of 88d being formed (see entry 2). Allyl chloride 90c was exclusively furnished by treatment of 87d with KCl in acetone at room temperature for 12 h (see entry 3). 

However, mechanistic experiments have involved the apices of the cyclopropane ring as targets for the nucleophilic group of the enzyme. Only the pro-R hydrogen was usually removed by the enzyme and transferred to NAD+, and the stereochemical course of the nucleophilic ring opening of the cyclopropanes was consistent with predictions on the basis of frontier orbital theory prediction [48]. 

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