Abstract
The cyclizing bis-phosphonium-salt formation of the open-chain bih-phosphine 17a (1,1,7,7-tetrabenzyl(P.O.P-podand-7)) with diethylene glycol derived dibromide 13a yields the 12-membered cyclic bib-phosphonium salt 20 (4,4,10,10-tetrabenzyl-12(.P.O.P-coronand-4)-4,10-diium dibromide) in yields as high as 50-60%. The 1,1,10,10-tetrabenzyl(P.O-2.P-podand-10) 17b forms with 13a the 15-membered ...
Abstract
The cyclizing bis-phosphonium-salt formation of the open-chain bih-phosphine 17a (1,1,7,7-tetrabenzyl(P.O.P-podand-7)) with diethylene glycol derived dibromide 13a yields the 12-membered cyclic bib-phosphonium salt 20 (4,4,10,10-tetrabenzyl-12(.P.O.P-coronand-4)-4,10-diium dibromide) in yields as high as 50-60%. The 1,1,10,10-tetrabenzyl(P.O-2.P-podand-10) 17b forms with 13a the 15-membered cyclic bis-phosphonium salt 21 (7,7,13,13-tetrabenzyl-15(O.P.O.P-coronand-5)-7,13-diium dibromide) with the same high yield. By quaternization of the bis-phosphine 17b with triethylene glycol derived dibromide 13b, the 18-membered 7,7,16,16-tetrabenzyl-18(O-2.P.O-2.P-coronand-6)-7,16-diium dibromide 24 is obtained in 501,10 yield, too. The Wittig reaction of the cyclic phosphonium salts with benzaldehyde yields the 12, 15-, and 18-membered cyclic bis-benzylphosphine dioxides 9, 10, and 11 as cis- and trans-isomers beside trans-stilbene, The 7,13-dioxido-7,13-dibenzyl-15(O-2.P.O-2.P-coronand-5 10 forms a crystalline 1: 1 Na-complex 23, which exists as a dimer. The structure of 23 was established by an X-ray analysis and spectroscopic data. The 7,16-dibenzyl-18(O-2.PO2.P-coronand-6) 28 that is available by reduction of 11 with CeCl3/LiAlH4 reacts with triethylene glycol derived dibromide 13b under Ruggly-Ziegler-dilution conditions to give the bicyclic bis-phosphonium salt 29 (1.10-dibenzyl(P[O-2](3).P-cryptand-8)-1,10-diium dibromide) in 18% yield. Again, by the Wittig procedure with benzaldehyde, the 7,16-dioxido(P[O-2](3)P-cryptand-8) 12 is obtained as the first diphosphacryptand. The FD-MS (CH2Cl2) of the cyclic bis-phosphine dioxides 10 - 12 show that they exist as [2M + Na](+) complexes. The complex formation constants K-a of 9 - 11 with alkali-metal cations are studied and compared with the complex formation of corresponding crown ethers.
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