(<i>tert</i>-Butylimino)tris(pyrrolidino)phosphorane (BTPP)

Schwesinger, Reinhard

doi:10.1002/9780470842898.rn00671

Cited by 3 publications

(4 citation statements)

References 53 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Anticipating the free guanidine N–H may interfere with attempts to alkylate C11, it was masked by formation of the corresponding oxazolidinone 18 . After significant screening efforts we found that the phosphazene base, tert -butylimino-tri(pyrrolidino)phosphorane (BTPP), was an excellent base for generating the C11 enolate . Addition of tert -butyl iodoacetate generated the C-alkylated product 19 in 54% yield.…”

supporting

confidence: 80%

A Direct C11 Alkylation Strategy on the Saxitoxin Core: A Synthesis of (+)-11-Saxitoxinethanoic Acid

2019

View full text Add to dashboard Cite

The bis-guanidinium ion family of natural products are revered for their utility in the study of ion channel physiology. While many congeners have been isolated with various oxidation and sulfation patterns, only two members of this family have been isolated bearing a carbon–carbon bond at C11, namely 11-saxitoxinethanoic acid and zetekitoxin AB. Herein we described a synthetic platform capable of efficiently targeting (+)-saxitoxin and 11-saxitoxinethanoic acid with an embedded C11 carbon–carbon bond. We demonstrate that this strategy enables direct enolate coupling in both an inter- and intramolecular fashion to create the C11–C15 carbon–carbon bond.

show abstract

supporting

confidence: 80%

A Direct C11 Alkylation Strategy on the Saxitoxin Core: A Synthesis of (+)-11-Saxitoxinethanoic Acid

2019

View full text Add to dashboard Cite

show abstract

“…However, the observed yield is only 63%. Despite BTPP being one of the least hindered phosphazenes, it seems its sterics are sufficient to partially inhibit the carboxylation of indole 1a …”

Section: Resultsmentioning

confidence: 99%

“…Despite BTPP being one of the least hindered phosphazenes, it seems its sterics are sufficient to partially inhibit the carboxylation of indole 1a. 65 Mechanistic Overview. Our overall experimental and computational results allow us to construct a comprehensive understanding of N-heteroaryl carbamate formation (Scheme 10).…”

Section: ■ Results and Discussionmentioning

confidence: 99%

N-Heteroaryl Carbamates from Carbon Dioxide via Chemoselective Superbase Catalysis: Substrate Scope and Mechanistic Investigation

et al. 2023

View full text Add to dashboard Cite

We report a mild superbase-catalyzed and nitrogen-selective carboxylation of N-heteroaryls, with subsequent alkylation enabling the synthesis of drug-like O-alkyl carbamates in good yields (av. 86%). Our findings suggest a partial revision of the current mechanistic understanding as superbases upon mixing with indoles and azoles generally form uncharged hydrogen-bonded complexes and not ionic salts as previously proposed. However, when these complexes are exposed to CO2, carbamate salts are formed. These can be categorized into two subgroups, stable and fluxional carbamate salts, where the latter undergo fast and reversible CO2 exchange, thus being poor substrates for alkylation. Experiments and DFT calculations indicate that the fluxional behavior is primarily caused by substrate-specific electronic destabilization effects. The degree of destabilization depends on the number of nitrogen atoms within and the functional group substitution on the heterocyclic ring structures. Fluxionality can be compensated for by the use of lower temperatures and/or higher CO2 pressures as both measures stabilize the carbamate salts sufficiently, enabling subsequent alkylation.

show abstract

“…Among the commercially available ones, P 2 -tBu is highly interesting as it allows reactions at ambient atmosphere due to good oxygen, hydrolysis, and thermal stability [51]. Contrarily, P 4 -tBu is extremely hygroscopic and requires rigorous exclusion of moisture [52]. In general, phosphazene bases are among the most efficient catalysts for oxa-Michael reactions and polymerizations [53].…”

Section: Methodsmentioning

confidence: 99%

Poly(ether)s derived from oxa-Michael polymerization: a comprehensive review

2023

View full text Add to dashboard Cite

Poly(ether)s represent an important class of polymers and are typically formed by ring-opening polymerization, Williamson ether synthesis, or self-condensation of alcohols. The oxa-Michael reaction presents another method to form poly(ether)s with additional functional groups in the polymer backbone starting from di- or triols and electron deficient olefins such as acrylates, sulfones, or acrylamides. However, research on oxa-Michael polymerization is still limited. Herein, we outline the principles of the oxa-Michael polymerization and focus on the synthesis and preparation of poly(ether-sulfone)s, poly(ether-ester)s, poly(ether)s, and poly(ether-amide)s. Further, challenges as well as future perspectives of the oxa-Michael polymerization are discussed. Graphical abstract

show abstract

(tert-Butylimino)tris(pyrrolidino)phosphorane (BTPP)

Cited by 3 publications

References 53 publications

A Direct C11 Alkylation Strategy on the Saxitoxin Core: A Synthesis of (+)-11-Saxitoxinethanoic Acid

A Direct C11 Alkylation Strategy on the Saxitoxin Core: A Synthesis of (+)-11-Saxitoxinethanoic Acid

N-Heteroaryl Carbamates from Carbon Dioxide via Chemoselective Superbase Catalysis: Substrate Scope and Mechanistic Investigation

Poly(ether)s derived from oxa-Michael polymerization: a comprehensive review

Contact Info

Product

Resources

About