Umsetzung einiger Dihydrobenzoxazaphosphorinone mit Nucleophilen; ungewöhnliche Oxidations‐, Insertions‐ und Umlagerungsprodukte und deren Charakterisierung durch Einkristall‐Röntgenstrukturanalyse

Reaction of some Dihydrobenzoxazaphosphorinones with Nucleophiles; Unusual Oxidation, Insertion, and Rearrangement Products and their Characterisation by Single‐Crystal X‐Ray Analysis The reaction of 2‐chloro‐1,2‐dihydro‐1‐methyl‐4 H ‐3,1,2‐oxazaphosphorin‐4‐one ( 2 ) and its 2‐diethylamino‐substituted derivative 3 with various nucleophiles yielded novel and sometimes unexpected products. Hydrolysis of 2 furnished the 2‐hydroxybenzoxazaphosphorinone 4 . In the presence of small amounts of water, two molecules of 4 were transformed into 5 , accompanied by cleavage of one of the heterocyclic rings. The reaction of 2 with sodium chlorodifluoroacetate led, possibly in an Arbuzov‐type reaction, to compound 6 . The 1,5‐diaza‐4,8‐cyclooctanedione system 7 was formed by reaction of 2 with 1,2,4,5‐tetrakis(trimethylsilyloxy)benzene with concomitant loss of the phosphorus‐containing group. 2,2′‐Bis(trimethylsiloxy)biphenyl reacted with 2 in the expected fashion to form the diphosphorus compound 8 . From 8 the chlorogold(I) complex 9 was obtained. The reaction of 3 with tetrachloro‐ and tetrabromo‐ o ‐benzoquinone did not lead to the expected spirocyclic products by oxidative addition of the quinone system to λ 3 P. Instead, cleavage and expansion of the heterocyclic ring system with formation of the tricyclic derivatives 10 and 11 took place. Compounds 5 ‐ 10 were subjected to X‐ray structure analysis. Compound 5 exists as two modifications 5a and 5b , which differ mainly in the relative orientation of the phenyl rings; intramolecular N–H…O hydrogen bonds are observed. Bond lengths at the halo‐substituted carbon atom in 6 indicate steric crowding. The central 8‐membered ring of 7 displays a “tub” conformation. Compound 8 undergoes a conformational change on complexation to the two gold(I) centres; one of the torsion angles C‐O(exocyc.)‐P‐N is ‐163° in 8 , but 95° in 9 . The structure determination of 10 served only to confirm the (unexpected) connectivity; the crystal quality was too poor to allow quantitative conclusions.