Ring-opened adduct

On the other hand, a recent crystallographic study revealed that the trans-2-phenylcyclopropylamine (8a) forms a cyclopropyl ring-opened adduct with MAO B at the flavin C(4a), and no evidence was obtained for inhibitor binding at Cys-365 [70,127]. From this observation, Edmondson and coworkers suggested [70] that the inhibition mechanism might be accommodated by a mechanism similar to that proposed by Sayre et al. for the quinone-mediated oxidative cleavage of cyclopropylamines [128]. 

Ring-opened adducts of carboplatin can form not only from reactions with nucleotides, but also by the attack of sulfur amino acids [44]. Reactions with thioether ligands are much more rapid compared with thiols. Surprisingly very stable ring-opened species such as [Pt(CBDCA-0)(NH3)2(L-HMet-S)] are formed, which has a half-life for Met-S,N closure of 28 h at 310 K. Such an intermediate could also play a role in the biological activity of this drug. 

The reaction with a, -epoxy carbonyl compounds 12 leads to the corresponding reductive ring-opened products, -hydroxy carbonyl compounds 13, in good yields (Scheme 22). Electrochemically generated benzeneselenolate [21,22] and sodium phenylseleno(triethoxy)borate (1) [35, 36], have been applied for this type of reaction as a nucleophilic selenolate. In the latter case, the reaction mechanism was suggested as shown in Scheme 23 [36]. Reaction of 1 with 12 first produces the ring-opened adduct 14, which is then reacted with an excess amount of 1 to produce the final product 13. This method is important as a simple synthetic procedure to aldols and -hydroxy esters that are rather difficult to obtain by other methods. The reactions have been extended to the reduction of more functionalized a, -epoxy carbonyl compounds [37] and have been successfully applied for the synthesis of several natural products [38]. 

Identification of 74 on incubation of MAO with 69 confirmed the initial formation of the 1-phenylcyclobutylaminium radical. That a variety of cyclopropylamines and cyclobutylamines inactivate MAO and result in ring-opened adducts is consistent with the intermediacy of the aminyl radicals. These results strongly suggest that the MAO-catalyzed oxidation of amines involves one-electron transfer as the first step. 

The reaction with mercury(II) acetate formed a stable ring-opened adduct which could be converted to 1-arylpropanol acetates by subsequent treatment with sodium borohydride. ... 

Several approaches to the taxane skeleton (97) have been published recently (see also reference 9). All have involved (2+2)- cycloaddition of the type reported by Berkowitz et ai. who have added cyclopentene and cyclohexene to the enone (98) to yield the cycloadducts (99). Successful addition of the alkene (lOO) to the same enone yields the ring-opened adduct (101). In a similar fashion the intramolecular addition of the enone (102) affords a (2+2)-adduct which can be treated with base to provide a route to the skeleton of the same natural product. ... 

The photochemical reaction of A -methylphthalimide with 1,1-diphenyl ethene affords the phthalimide adduct (329) and the ether (330) in 44 and 12 % yield respectively. With imide (331) the byproducts are the ring opened adduct (332) and the ether (330) in yields of 31 and 44% yield respectively. The authors suggest that the formation of the ether is the result of a second electron transfer as illustrated in Scheme 11. ... 

Monoalkoxy salts react with carbanions such as those derived from malononitrile, cyanacetic esters, benzyl cyanide, dimedone or tetra-phenylcyclopentadiene [63,64], Attack may take place at any of the ring carbon atoms, the site of attack being affected by solvent and by substituent effects, and the resulting products include cyclo-propene ethers, methylenecyclopropene derivatives and ring-opened adducts, e.g. 

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