7 research outputs found
Dehydrodechlorination of Methylene Chloride, Chloroform, and Chlorodiphenylmethane in the Presence of Ga/N Lewis Pairs
Transmetalation occurs
upon addition of GaCl<sub>3</sub> to (quinolin-8-yl)trimethylstannane.
The compound dissolves immediately in pyridine, and recrystallization
gives dichloropyridinyl(quinolin-8-yl)gallium(III).
In chloroform, the compound bis-μ-(quinolin-8-yl)-μ-chloro-dichlorodigallium(III)
tetrachlorogallate could be isolated in small quantities;
however, the major product was trichloro(quinolinium-8-yl)gallate(III)
zwitterion. The zwitterion also formed upon addition of methylene
chloride or chlorodiphenylmethane. We hypothesize that
the highly electrophilic digallyl cation abstracts chloride to form
a carbocation and that proton transfer from the carbocation to the
quinoline nitrogen affords transient carbenes. In particular, diphenyl
carbene forms from dehydrodechlorination of chlorodiphenylmethane
in toluene/cyclohexene to give a well-defined mixture of products
due to cyclopropanation and C–H insertion reactions. Dichloropyridinyl(quinolin-8-yl)gallium(III)
undergoes reaction with chloroform only at elevated temperature to
yield quinolinium tetrachlorogallate salt as the product.
This salt also forms in the reaction of chloroform with GaCl<sub>3</sub> and quinoline at elevated temperature. The zwitterion could be converted
to quinolinium tetrachlorogallate upon heating, which
supports the idea that it was formed initially as an intermediate.
Thus, the Ga/N Lewis pairs appear capable of dehydrodechlorination
of chloroalkanes
Dehydrodechlorination of Methylene Chloride, Chloroform, and Chlorodiphenylmethane in the Presence of Ga/N Lewis Pairs
Transmetalation occurs
upon addition of GaCl<sub>3</sub> to (quinolin-8-yl)trimethylstannane.
The compound dissolves immediately in pyridine, and recrystallization
gives dichloropyridinyl(quinolin-8-yl)gallium(III).
In chloroform, the compound bis-μ-(quinolin-8-yl)-μ-chloro-dichlorodigallium(III)
tetrachlorogallate could be isolated in small quantities;
however, the major product was trichloro(quinolinium-8-yl)gallate(III)
zwitterion. The zwitterion also formed upon addition of methylene
chloride or chlorodiphenylmethane. We hypothesize that
the highly electrophilic digallyl cation abstracts chloride to form
a carbocation and that proton transfer from the carbocation to the
quinoline nitrogen affords transient carbenes. In particular, diphenyl
carbene forms from dehydrodechlorination of chlorodiphenylmethane
in toluene/cyclohexene to give a well-defined mixture of products
due to cyclopropanation and C–H insertion reactions. Dichloropyridinyl(quinolin-8-yl)gallium(III)
undergoes reaction with chloroform only at elevated temperature to
yield quinolinium tetrachlorogallate salt as the product.
This salt also forms in the reaction of chloroform with GaCl<sub>3</sub> and quinoline at elevated temperature. The zwitterion could be converted
to quinolinium tetrachlorogallate upon heating, which
supports the idea that it was formed initially as an intermediate.
Thus, the Ga/N Lewis pairs appear capable of dehydrodechlorination
of chloroalkanes
Correction to “Diverting Reactive Intermediates Toward Unusual Chemistry: Unexpected Anthranil Products from Davis–Beirut Reaction”
Correction to “Diverting Reactive Intermediates
Toward Unusual Chemistry: Unexpected Anthranil Products from Davis–Beirut
Reaction
Diverting Reactive Intermediates Toward Unusual Chemistry: Unexpected Anthranil Products from Davis–Beirut Reaction
The
discovery of a new variation on the Davis–Beirut reaction
is described in which an atypical heterocyclic framework (the anthranil
or benzo[<i>c</i>]isoxazole framework) is formed as the
result of diversion of a key reactive intermediate away from its expected
reactivitya potentially general approach to reaction design
and development. Experimental and computational support for the proposed
mechanism and origins of altered reactivity are described
Davis–Beirut Reaction: Alkoxide versus Hydroxide Addition to the Key <i>o</i>‑Nitrosoimine Intermediate
Reaction options,
alkoxide vs hydroxide vs amine addition to the
key intermediate (<i>o</i>-nitrosoimine) generated in the
Davis–Beirut reaction of an <i>o</i>-nitrobenzylamine
substrate, are reported to explain the nucleophilic addition selectivity
of this one-pot indazole-forming process. The hydroxide addition/deprotection
pathway as well as the fate of the resulting <i>o</i>-nitrosobenzaldehyde
were both uncovered with several <i>o</i>-nitrobenzylamine
substrates, and design elements required for an efficient double Davis–Beirut
reaction, inspired by new mechanistic insights, were defined
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N–N Bond Formation between Primary Amines and Nitrosos: Direct Synthesis of 2‑Substituted Indazolones with Mechanistic Insights
A concise,
one-step route to indazolones from primary alkyl amines
and <i>o</i>-nitrobenzyl alcohols is reported. The key step
in this readily scalable indazolone forming process involves base-mediated <i>in situ o</i>-nitrobenzyl alcohol → <i>o</i>-nitrosobenzaldehyde conversion. Although this functional group interconversion
is known to be useful for 2<i>H</i>-indazole synthesis,
its reactivity was modulated for indazolone formation
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High-Potency Phenylquinoxalinone Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) Activators
We
previously identified phenylquinoxalinone CFTR<sub>act</sub>-J027
(<b>4</b>) as a cystic fibrosis transmembrane conductance
regulator (CFTR) activator with an EC<sub>50</sub> of ∼200
nM and demonstrated its therapeutic efficacy in mouse models of constipation.
Here, structure–activity studies were done on 36 synthesized
phenylquinoxalinone analogs to identify compounds with improved potency
and altered metabolic stability. Synthesis of the phenylquinoxalinone
core was generally accomplished by condensation of 1,2-phenylenediamines
with substituted phenyloxoacetates. Structure–activity studies
established, among other features, the privileged nature of a properly
positioned nitro moiety on the 3-aryl group. Synthesized analogs showed
improved CFTR activation potency compared to <b>4</b> with EC<sub>50</sub> down to 21 nM and with greater metabolic stability. CFTR
activators have potential therapeutic indications in constipation,
dry eye, cholestatic liver diseases, and inflammatory lung disorders