Efficient synthesis of cyclic beta-oxophosphoranes by microwave-assisted reaction of cyclic phosphine oxides and dialkyl acetylenedicarboxylates

• Published in: Synthesis (Stuttgart) no. 8; pp. 1365 - 1369
• Main Authors: Keglevich, G, Dudas, E, Sipos, M, Lengyel, D, Ludanyi, K
• Format: Journal Article
• Language: English
• Published: STUTTGART Thieme Medical Publishers 19.04.2006
• Subjects: Chemistry; Chemistry, Organic; Physical Sciences; Science & Technology; ylides; PHOSPHOLES; DMAD; DIMETHYL ACETYLENEDICARBOXYLATE; P-HETEROCYCLES; alkyne derivatives; phosphoranes; NMR; inverse-Wittig reactions; 1-OXIDES; microwave synthesis; REDUCED PYRAMIDAL CHARACTER; INVERSE WITTIG REACTION; cyclic phosphine oxides
• DOI: 10.1055/s-2006-929395
• ISSN: 0039-7881

The inverse Wittig-type reaction of a series of 2,4,6-trialkylphenyl cyclic phosphine oxides 3, 5, 7, 9, 11, 13, 15, 18 and 20 and dialkyl acetytenedicarboxylate giving beta-oxophosphoranes 4, 6, 8, 10, 12, 14, 16, 19 and 21, respectively, can be accomplished in a convenient way under microwave conditions. At 150 degrees C, the MW-assisted reaction is more efficient and becomes 50-fold faster as compared to the thermal transformation. A further advantage is that the 2,5-dihydrophosphole moiety of the 2,4,6-triisopropylphenyl derivative 3 does not undergo double-bond rearrangement and that the 2,4,6-trimethylphenyl substrates 11 and 13, otherwise inactive in the reaction under discussion, Could also be converted to beta-oxophosphoranes 12 and 14. A series of new products 4Bb, 12, 14, 16b, 19 and 21 have been made available.