Toward a Clean Alternative to Friedel−Crafts Acylation:  In Situ Formation, Observation, and Reaction of an Acyl Bis(trifluoroacetyl)phosphate and Related Structures

Abstract

Reaction of acyl trifluoroacetates with phosphoric acid in the presence of trifluoroacetic anhydride (TFAA) leads to the ready formation of acyl bis(trifluoroacetyl)phosphates, which are powerful acylating agents. Formation of these species and the subsequent acylation reaction are carried out, without added solvent, in a single in situ reaction process. In this reaction system, anisole is rapidly acylated at ambient temperature using a variety of carboxylic acids giving the para isomer exclusively. TFAA acts as an activating agent and can be recovered from the reaction system as trifluoroacetic acid (TFA) and converted back to TFAA using a dehydrating agent, while phosphoric acid behaves as a covalent catalyst in the process. This reaction system has many features which are required elements of a clean alternative to the Friedel−Crafts process.

Relative impact of 3- and 5-hydroxyl groups of cytosporone B on cancer cell viability

“…Introducing the n -octanoyl group at the 2-position of intermediate 8 to produce 9 (step d) employed the potent acylating agent octanoyl bis(trifluoroacetyl)phosphate, which was formed in situ from n -octanoic acid and trifluoroacetic anhydride in phosphoric acid. 18,19 Its potency may account for the debenzylation that occurred at the 5-position to give a 1: 10 mixture of the 3,5-dibenzyl ether 9 and 3-benzyl ether 10. Deprotection of 3-benzyl ether 10 using boron tribromide at −78 °C produced Csn-B (1).…”

Characterization of molecular and structural determinants of selective estrogen receptor downregulators

“…As a result, a new synthesis was designed that relied on a high yielding Friedel-Crafts acylation and Grignard coupling reaction to generate the triphenylethylene core ( Fig. 2) [10,11]. The dehydration generated both stereoisomers of the double bond, but after deprotection of the phenol, the double bond of the triphenylethylene interconverted readily at room temperature, as had been shown previously [9].…”

Tunable Oleo-Furan Surfactants by Acylation of Renewable Furans

“…As depicted in Figure 2, long (>C10) alkyl chains are obtained from hydrolysis of triglycerides to fatty acids such as lauric acid (C12), myristic acid (C14), or stearic acid (C18) and can be converted to anhydrides by numerous existing methods including dehydration in the presence of water sorbents or other short-chain recyclable anhydrides. 22,23 Here, we demonstrate the coupling of these long alkyl chain anhydrides with furans by Friedel–Crafts acylation with heterogeneous catalysts. As shown in Figure 2B, the reaction of lauric anhydride with furan on either Lewis acid zeolites (such as Sn-BEA, Sn-MWW, or Sn-SPP) or Brønsted acid zeolites (such as Al-BEA or Al-SPP) exhibited significant activity for acylation (see Supporting Information for details).…”

“…By this method 2-dodecanoylfuran was recovered by evaporating any remaining furan, solvent, or trifluoroacetic acid, which can be recycled to TFAA. 22 …”