The Interlocking of Salicylic Aldehydes and Ketones with a 2h‐1,2,4,3‐Triazaphosphole

Abstract

Salicylic aldehyde (2a) adds to 2-methyl-5-phenyl-2H-compound forms dimers by a double hydrogen bond bet-1,2,4,3-triazaphosphole (1) to yield the bicyclic phosphonic ween two HN-PO units. Substituted salicylic aldehydes as amide 3a. The OH group adds to the P=N bond, the carbon well as ortho-hydroxyacetophenone and benzophenone reatom of the carbonyl group is inserted into the other P-N act in the same way. bond, and the phosphorus atom is oxidized. In the crystal the The phosphorus atom of a 2H-1,2,4,3-triazaphosphoIe such as 1 [1,2] is capable of both accepting and donating a pair of electrons. As a consequence it adds alcohols and other protic nucleophiles to its P = N bond and is oxidized by sulfur or halogen. Alcohols or phenols with appropriate additional functions can at the same time make use of both triazaphosphole reactivities. Glycols, 2-azido alcohols or oheterodienylphenols thus yield spirocyclic phosphorane~[~I. Salicylic aldehyde offers itself as another possible difunctional partner, although the nature of its second function is different. For the reaction with the triazaphosphole phosphorus atom it provides a nucleophilic hydroxyl and an electrophilic carbonyl group at a suitable three-bond distance. Results and DiscussionFrom the benzene solution of 2-methyl-5-phenyl-2H-1,2,4,3-triazaphosphole (1) and the 2-hydroxybenzaldehydes 2a-d (R' = H, R2-R5 = H, OMe, NOz) or 2-hydroxyacetophenone (2e) (R1 = Me, R2-R5 = H) or 2-hydroxybenzophenone (20 (R' = Ph, R2-R5 = H) products 3a-f precipitate. They are colorless except for the orangeyellow nitro derivative 3d. The reaction requires several days at ambient temperature for completion and of course proceeds more rapidly under reflux conditions. The compounds 3 consist of an equimolar combination of the two components as revealed by elemental analysis. It turned out, however, that the product in this case is not a spirocyclic A single-crystal X-ray analysis (see below) revealed the structure of example 3a. The NMR spectra of all other products (Tables 1 and 2) also correspond to those of 3a.The phenolic oxygen atom is bound to the phosphorus atom as expected, and the phosphorus atom is oxidized[*]X-ray structure analysis.

Amides of Trivalent Phosphorus Acids as Phosphorylating Reagents for Proton-Donating Nucleophiles

“…In recent years, it has been shown that the process in question is more general. Thus, hypophosphorus amides undergo alcoholysis. − Interestingly, phosphimine derivatives also react with alcohols and phenols , (Scheme ).

17

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“…Thus, hypophosphorus amides undergo alcoholysis. [141][142][143] Interestingly, phosphimine derivatives also react with alcohols and phenols 144,145 (Scheme 17).…”

Syntheses of 1,2‐Oxaphospholane 2‐Oxides and 1,2‐Oxaphosphole 2‐Oxides

“…The reaction process was assumed as nucleophilic addition of the hydroxyl group to the P=N bond, the subsequent nucleophilic attack of the nitrogen in 2H-1,2,4,3-triazaphosphole 308 to the carbonyl groups and the generated alkoxide attacking to the phosphorus atom followed by a ring contraction (Scheme 78). [108] Treatment of tri(5-tert-butyl-2-methoxyphenyl)methane (312) with butyl lithium followed by the reaction with ). [109] Reactions of 1-phenyliminobenzo[c] [1,2]oxaphosphole 314 with hexafluoroacetone and phenylisothiocyanate gave the corresponding spirocycloadducts 315 and 318, which underwent thermolysis to generate 3H-benzo[c][1,2]phosphole 1oxide 316 and 1-sulfide 319, respectively, accompanied with imine 317 and carbodiimide 320 (Scheme 80).…”

“…The reaction process was assumed as nucleophilic addition of the hydroxyl group to the P=N bond, the subsequent nucleophilic attack of the nitrogen in 2 H ‐1,2,4,3‐triazaphosphole 308 to the carbonyl groups and the generated alkoxide attacking to the phosphorus atom followed by a ring contraction (Scheme 78). [108] …”