The Chemistry of Chloroformates

Matzner, M.; Kurkjy, Raymond P.; Cotter, Robert J.

doi:10.1021/cr60232a004

Cited by 139 publications

(63 citation statements)

References 155 publications

(176 reference statements)

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“…In the present study, unlike the solvolyses of phenyl chlorothionoformate (3), where the two reaction channals (addition-elimination and ionization pathways) were observed, the solvolyses of 1 have a pathway involving bimolecular attack by solvent at thiocarbonyl carbon, with what is suggested to be the addition step of an addition-elimination pathway being rate determining (Scheme 1).…”

Section: Discussioncontrasting

confidence: 53%

“…[1][2][3] In particular, they are very important substrates for the introduction of protecting groups during peptide synthesis. 4 We previously reported that the solvolyses of phenyl chloroformate (PhOCOCl, 2) 5 in a wide range of solvents and phenyl chlorothionoformate (PhOCSCl, 3) 6 in solvents of low ionization power and/or high nucleophilicity follow an addition-elimination mechanism (Scheme 1) using either the simple or extended Grunwald-Winstein equation 7 [eqs. (1) and (2), respectively].…”

Section: Introductionmentioning

confidence: 99%

“…A recently published study of the solvolysis of PhOCSCl (3) 6 is extended to PhOCSF (1). In spite of intensive experimental examination of the mechanism of alkyl and aryl halogenoformate reactions for many years, the mechanisms of most of these reactions are still not established.…”

Section: Introductionmentioning

confidence: 99%

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Correlation of the Rates of Solvolysis of Phenyl Fluorothionoformate

Choi¹,

Seong²,

Lee³

et al. 2011

Bulletin of the Korean Chemical Society

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The specific rates of solvolysis of phenyl fluorothionoformate (PhOCSF, 1) have been determined in 22 pure and binary solvents at 10.0 o C. The extended Grunwald-Winstein equation has been applied to the specific rates of solvolysis of 1 over the full range of solvents. The sensitivities (l = 1.32 ± 0.13 and m = 0.39 ± 0.08) toward the changes in solvent nucleophilicity and solvent ionizing power, and the kF/kCl values are similar to those previously observed for solvolyses of acyl haloformate esters, consistent with the addition step of an additionelimination pathway being rate-determining. The large negative values for the entropies of activation are consistent with the bimolecular nature of the proposed rate-determining step. The results are compared with those reported earlier for phenyl chloroformate and chlorothionoformate esters and mechanistic conclusions are drawn.

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Section: Discussioncontrasting

confidence: 53%

Section: Introductionmentioning

confidence: 99%

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Correlation of the Rates of Solvolysis of Phenyl Fluorothionoformate

Choi¹,

Seong²,

Lee³

et al. 2011

Bulletin of the Korean Chemical Society

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“…In general, the phenols are precursors of other useful compounds, such as chloroformates [12,13]. We have already reported the synthesis and characterization of the first bis(chloroformates) containing silicon or germanium as central atom [14], 4,4 -(dimethylsilylene)bis(phenyl chloroformate) and 4,4 -(dimethylgermylene)bis (phenyl chloroformate) (Fig.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and characterization of new bi-functional monomers based on germarylene or silarylene units: 4,4′-(R1R2-silylene)bis(phenyl chloroformates) and 4,4′-(R1R2-germylene)bis(phenyl chloroformates)

Terraza

Tagle

Concha

et al. 2007

Designed Monomers and Polymers

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Abstract-Following the reaction route between a diphenol and phosgene/toluene solution in basic medium, six new bis(chloroformates) containing germarylene or silarylene units were synthesized with good yield. The variation on the structure is due to the nature of the groups bonded to the heteroatom. Therefore, combinations of Me, Et and Ph groups were used. 4,4 -(Diethylsilylene)bis(phenyl chloroformate), 4,4 -(ethylmethylsilylene)bis(phenyl chloroformate) and 4,4 -(diethylgermylene)bis(phenyl chloroformate) were obtained as a slightly yellow oil, while 4,4 -(diphenylsilylene)bis(phenyl chloroformate), 4,4 -(methylphenylsilylene)bis(phenyl chloroformate) and 4,4 -(diphenylgermylene)bis(phenyl chloroformate) were obtained as a white solid. The new bi-functional monomers were characterized by FT-IR, 29 Si-, 13 C-and 1 H-NMR spectroscopy and elemental analysis. The T m of the products in general was higher in samples containing germanium as the central atom, compared to those containing silicon.

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“…4 s of ester IIb melting a t 199-200' (Fisher--Johns melting point apparatus). A pure sample was recrystallized from acetonemethanol as waxy needles,[aJnZO $28" (c,7 .15); v,,,,,, 1 720, 1 282, 1 171, and 1 032 c111- Sodium borohydride (0.16 g) in diethylene glycol dimethyl ether (diglyme, 6 ml) was added to an icecold solution of pivalate IIb (0.51 g) in tetrahydrofuran (20 ml) -boron trifluoride etherate (8 ~n l ) .…”

Section: -(22-di~~tetkyl)propoxy-5o-clrola?ae (Ic)mentioning

confidence: 99%

Steroids and Related Natural Products: Xxxi. Selective Reduction of Esters. Part B. Carbonates

Pettit¹,

Evers²

1966

Can. J. Chem.

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Direct reduction of several pivalate esters to neopentyl ethers has been accomplished with boron trifluoride -s o d i l~n~ borohydride. The utility of the reduction reaction was illustrated ~vith esters Ic, IIb, and IVa. Under the same conditions, a selection ( I d , IId, and I V a ) of carbonate esters was found to be relatively resistant to reduction. In this respect, the carbonate esters resembled benzoate esters, and selective reduction of a Icetone ( I l d ) or another ester ( I V a --t I V b ) in their presence was possible. For comparison, one xanthate ester ( I e ) was allowed to react .with boron trifluoride -s o d i~~n~ borohydride, and only the corresponding alcohol ( l a ) was ~solated. Raney nickel desulfurization of xanthate l a was sho1v11 to provide alcohol la and hydrocarbo~l If as principal products.Prior studies of ester + ether reduction reactioils with diborane -boron trifluoride type reagents indicated that the alcohol segment of the ester influences the yield of ether \vhile the carbonyl portion can influence the ease of reduction. For example, a series of otherwise equivalent n-, s-, and t-butyl esters, when allowed to react \\-it11 boron trifluoride -sodium borohydride, \\rere transformed to the corresponding ethers \vith marlted increments in yield (7-76%) as alliyl branching adjacent to the ester alcohol group increased (2). Under the same conditions, benzoate esters were found to be essentially unaffected (1). T o define further the scope of these observations and to increase biological knowledge of steroidal ethers (e.g. see ref.3 ) , \ye have examined the reaction between boron trifluoride -sodium borohydride and several pivalate-and carbonate-type esters.Appropriate esters derived froin primary alcohol Ia \Irere chose11 for initial illode1 experiments. The requirements for 24-hydroxy-$3-cholane (Ia) \\.ere conveniently met by modifying a prior route (see ref. 2 for leading literature citations) t o this substance. Cholic acid \\-as oxidized to dehydrocholic acid by a modification of the Jones' chromic acid technique, and after Wolff-ICishner reduction, the $3-cholanic acid \\-as reduced with conlmercial diborane in tetrahydrofuran.* Treating alcohol In in pyridine solution 114th pivaloyl chloride gave ester Ib. Previous experience (2) suggested that reduction of pivalate I b \\ould provide neopentyl ether Ic in approxiinately 10% yield, and indeed 13% conversion was realized. Although the actual reagent used in this experiment was diborane -boron trifluoride,%ll subsequent reduction reactions \\;ere carried out \vith a boron trifluoride -sodiulu borohydride reagent.G Next, pivalate ester I I b , prepared from 'For part XA'X i n tltis series, refer to ref. 1. T h e present contribtction i s based o n part of the

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The Chemistry of Chloroformates

Cited by 139 publications

References 155 publications

Correlation of the Rates of Solvolysis of Phenyl Fluorothionoformate

Correlation of the Rates of Solvolysis of Phenyl Fluorothionoformate

Synthesis and characterization of new bi-functional monomers based on germarylene or silarylene units: 4,4′-(R1R2-silylene)bis(phenyl chloroformates) and 4,4′-(R1R2-germylene)bis(phenyl chloroformates)

Steroids and Related Natural Products: Xxxi. Selective Reduction of Esters. Part B. Carbonates

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