200111-86-0

Upstream product

• 107-10-8 propylamine 
• 14039-13-5 C₂₂H₂₁O₃⁽¹⁺⁾ 
• 437-30-9 4,4',4-trimethoxytrityl tetrafluoroborate 

Downstream Products

• 3010-81-9 tris(4-methoxyphenyl)methanol 
• 4449-98-3 n-propylammonium perchlorate 

Relevant academic research and scientific papers

4,4′-Dimethoxytrityl and 4,4′,4″-trimethoxytrityl as protecting groups for amino functions; selectivity for primary amino groups and application in 15N-labelling

4,4′-Dimethoxytrityl tetrafluoroborate (DMT+ BF4-) and 4,4′,4″-trimethoxytrityl tetrafluoroborate (TMT+ BF4-) are useful reagents for protecting primary and some secondary amines. Protected amines are obtained either by reaction of DMT+ BF4- or TMT+ BF4- with the amine or by alkylating DMT- or TMT-amine (available from DMT+ BF4- and TMT+ BF4- by treatment with ammonia). Alkylation of DMT- or TMT-amine stops after monoalkylation. Deprotection of the alkylated DMT- and TMT-amine is achieved by treatment with an acid of appropriate molarity (e.g. 0.1 M HCl in 1:1 tetrahydrofuran-water for TMT-amines). The value of the methodology described is illustrated by a synthesis of (15NH2) adenosine. X-Ray molecular structures of one DMT and two TMT derivatives are reported.

Reactivities of diarylmethyl and triarylmethyl cations with primary amines in aqueous acetonitrile solutions. The importance of amine hydration

By use of the technique of laser flash photolysis, rate constants k(RNH2 have been directly measured for the reactions of primary amines RCH2NH2 (R = CH3CH2, CH3OCH2, NCCH2, CF3) with diarylmethyl cations (D+) in acetonitrile/water solutions. In 100% acetonitrile the reactions approach the diffusion limit, 5 × 109 M-1 s-1, although they are slower, k(RNH2) for a given cation increasing with increasing amine basicity and for a given amine increasing with decreased electron donation from substituents in D+. In the mixed solvents the rate constants decrease in a regular fashion with increasing water content. The changes can be large, being on the order of 10-100 proceeding from 100% acetonitrile to 100% water. Moreover, the rate-retarding effect of water is more pronounced with more basic amines, with the consequence that in water-rich solutions the reactivity order no longer parallels amine basicity. Plots of log k(RNH2) versus pka(RNH3+) not only are curved but also show a change in the sign of their slope on progressing from weakly basic amines (positive βnuc) to strongly basic ones (negative βnuc). This behavior is explained by a mechanism in which a hydrated amine RNH2-HOH is unreactive and an equilibrium desolvation to form the unhydrated amine precedes reaction with the cation. Quantitative treatment is carried out, using the rate constants in 100% acetonitrile to model the reaction of the free amine. This approach reproduces the experimental data within an average of ±0.04 log unit and results in equilibrium constants for the desolvation with the expected β= -0.2 dependency on amine basicity. Rate constants have also been measured in 33% acetonitrile/water for a series of triarylmethyl cations ranging from 4,4'-(Me2N)2T+ to 4,4'-(CF3)2T+. The βnuc values for these are all positive, with a clear trend for βnuc to decrease with increasing cation reactivity, this being true even for the relatively stable cations 4,4'-(Me2N)2T+, 4-Me2NT+ and 4,4′,4″-(MeO)3T+. Thus, amine nucleophiles do not adhere to the N+ constant selectivity relation, even for stable cations.