Ring opening reactions chloride

The chemical consequences of /3-protonation are illustrated further by the ring-opening reactions of furans with methanolic hydrogen chloride and of (V-substituted pyrroles with hydroxylamine hydrochloride (Scheme 11) (82CC800). 

Acylations were often carried out with diaziridines. Twofold acylation is normally observed when two NH groups are present. Most acylations were performed with benzoyl chloride, acetyl chloride or phenyl isocyanate (B-67MI50800). Ring opening reactions during acylation, foreseeable for intermediates of electrophilic attack on nitrogen, were observed only seldom, provided mild conditions were used. 

OKO-l,3,7-triazanaphthalene (450) forms acyloxy derivatives in situ with phosphorus oxychloride and pentasulfide which undergo nucleophilic displacement with chloride ion and with a complex sulfide ion, respectively, to form the 4-chloro and 4-thioxo derivatives. The 4-carboxymethylthio compoimd failed to undergo the ring-opening reaction (see below) characteristic of more activated azino- and diazino-pyrimidines, but it did yield about 10% of the 4-0X0 displacement product. 

A mechanism analogous in many ways to that of the acid-catalyzed ring opening reaction was advanced for the reaction of the thiirane oxide with alkyl chloromethyl ethers S . The first step is the displacement of the chloride by the sulfoxy oxygen (equation 24). In view of the above mechanistic interpretation, it is quite surprising that the parent thiirane oxide (16a) was found to be protonated on sulfur and not at oxygen in FSOjH-SbFfi at — 78 °C, according to NMR studies s . 

Ring opening reaction of alkylidenecyclopropanone acetals readily proceeds in the presence of Lewis or Bransted acids to produce l-alkylidene-2-oxyallyl cation, which is provided for the reaction with nucleophiles such as chloride, alcohols, siloxyalkenes, and furans. The reaction of this cation with the carbon nucleophiles gives products of [4 + 3] and [3 + 2] cycloaddition as well as those of nucleophilic addition. The modes of addition reactions are controlled by the oxy group of the cation and by the reaction conditions including solvent. 

Wordy Over the past few years, we have encountered numerous examples of water as the perfect solvent. We observed this first in osmium-catalyzed dihydroxylation reactions and also in nucleophilic ring-opening reactions of epoxides. We also observed this in cycloaddition reactions and in most oxime ether, hydrazone, and aromatic heterocycle condensation processes.Finally, we observed it in formation reactions of an amide from a primary amine and an acid chloride using aqueous Schotten-Baumann conditions. ... 

The amount of EGA (the current efficiency of EGA generation) is measured in both acetone and methylene chloride-THF. Both Figs. 1 and 2 show that a sharp increase in the concentration of EGA is observed in the electrolysis of lithium, sodium, and magnesium perchlorate solution, being consistent with the result of the oxirane ring opening reaction to ketones (Table 2). 

Acetate pyrolysis is illustrated by the synthesis of penta-1,4-diene (Expt 5.14) from 1,5-diacetoxypentane. This is prepared from 5-chloropentyl acetate which is conveniently obtained from tetrahydropyran by treatment with acetyl chloride this ring-opening reaction offers interesting comparison with the methods for the preparation of a, cu-dihalides discussed in Section 5.5.1, p. 555. 

Addition of sulfur chlorides and sulfenyl halides to hydrocarbon olefins is a classic example of electrophilic reaction which usually proceeds under mild conditions and results in stereospecific trans-addition via intermediate formation of cyclic episulfonium cation [134]. Ring-opening reactions of episul-fonium cation with nucleophile is responsible for formation of regioisomers when nonsymmetrical olefins are used as substrates. 

The transition states for the ring opening reaction of an aziridinium ion by chloride ion were calculated using the IRC and QRC methods.56 Whereas the IRC method found only one transition state for the reaction, the QRC method suggested that there were two transition states that occurred sequentially along the reaction coordinate without an intervening intermediate. 

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