1,3,5‐Triaza‐7‐phosphaadamantane (PTA): A Practical and Versatile Nucleophilic Phosphine Organocatalyst

Abstract

In this paper, the air-stable and readily available 1,3,5-triaza-7-phosphaadmantane (PTA) is reported as a practical and versatile nucleophilic phosphine organocatalyst. Under the mediation of 15-30 mol % of PTA, various electrophiles like aldehydes and imines readily undergo the MoritaBaylis-Hillman reactions with a variety of activated olefins, giving the corresponding adducts in high yields. In the phosphine-catalyzed [3 + 2] cycloaddition reaction of 4-substituted 2,3-butadienoates with N-tosylimines, PTA is also proven to be a comparable catalyst as tributylphosphine (PBu 3 ). By systematic comparison with other structurally similar N,P catalysts, it is concluded that the superiority of PTA in the above nucleophilic catalysis is attributable to its comparable nucleophilicity with that of trialkylphosphines. The feasibility to use PTA as an alternative catalyst in place of the air-sensitive trialkylphosphines is also discussed.

Phosphane‐Catalyzed [3+2] Annulation of Allenoates with Aldehydes: A Simple and Efficient Synthesis of 2‐Alkylidenetetrahydrofurans

“…Intrigued by these elegant studies, especially from the Kwon group, we suspected that the introduction of a substituent at the γ carbon of an allenoate may be able to alter the normal regioselectivity of γ addition of aldehydes to allenoates. Although it is known that γ‐substituted allenoates still retain similar reactivity patterns with activated olefins and imines to those of nonsubstituted allenoates 7b,j,k. To evaluate this hypothesis, we began our investigation with allenoates bearing a small substituent like methyl ( 2 a ) or a bulky substituent like phenyl ( 2 b ) or tertiary butyl ( 2 c ) at the γ carbon.…”

Nafion®-Containing Solid Lipid Nanoparticles as a Tool for Anticancer Pt Delivery: Preliminary Studies

“…The phosphine 1,3,5-triaza-7-phosphaadamantane (PTA) (see Table 1) [7] looks particularly suitable for pharmaceutical application because it possesses reactivity and size comparable to that of alkylphosphines [8] with the addition of valuable properties like hydrosolubility, stability to oxidation, and lack of toxicity. PTA can be selectively alkylated or protonated on nitrogen, thus maintaining its coordinative ability, which is achieved by phosphorus.…”

Synthesis and structure of stable water-soluble phosphonium alkanoate zwitterions derived from 1,3,5-triaza-7-phosphaadamantane

“…This again shows the presence of C(sp 3 )-C(sp 3 ) single bonds in these compounds. [23] and P-(2-carboxyethyl)-pta [25]. Figure S2.…”

“…In the known P-alkylated pta derivatives (P-methyl-pta [23] and P-(2-carboxyethyl-pta [25]) the C1-P, C2-P and C3-P bond distances are significantly shorter than in pta [37]. The same is observed in case of 1 and 2; in general, the C1-, C2-, C3-P bond distances are closer to those in P-methyl-pta than to those in P-(2-carboxyethyl)-pta ( Table 2).…”

“…Furthermore, in the Morita-Baylis-Hillman α-hydroxyalkylation of ethyl acrylate, catalyzed by pta, the corresponding phosphonium salt, 7-(2-carboxyethyl)-1,3,5-triaza-7-phosphoniatricyclo[3.3.1.1 3,7 ]decane (P-(2-carboxyethyl)-pta) was isolated [24] and its solid state structure was determined [25]. To remove the apparent contradiction in the literature, we decided to reinvestigate the formation of phosphonium salts in the reaction of pta with olefindicarboxylic acids in water in the absence of strong acids.…”