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Propyne Iminium Salts and Phosphorus( III ) Nucleophiles: Synthesis of (3‐Morpholinoallenyl)phosphanes and ‐phosphane Oxides or 1‐(Morpholinopropargyl)phosphanes and ‐phosphonates
Author(s) -
Reisser Martin,
Maier Alexandra,
Maas Gerhard
Publication year - 2003
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.200300080
Subject(s) - chemistry , iminium , nucleophile , allene , medicinal chemistry , cycloaddition , propyne , moiety , trifluoromethanesulfonate , nucleophilic addition , stereochemistry , organic chemistry , catalysis
Treatment of 4‐(1,3‐diphenyl‐l‐propynylidene)morpholinium triflate ( 1a ) with the neutral phosphorus nucleophiles Me 3 Si−PPh 2 , Me 3 Si−P(Ph)C 5 H 11 , and Me 3 SiO−PPh 2 affords (3‐morpholinoallenyl)phosphanes 4 and 5 and (3‐morpholinoallenyl)phosphane oxide 11 , respectively. In contrast to these conjugate addition reactions at the ambident propyne iminium moiety of 1a , nucleophilic attack by Me 3 Si−PEt 2 and Me 3 SiO−P(OEt) 2 takes place at the iminium function and gives (1‐morpholinopropargyl)phosphane 6 and (1‐morpholinopropargyl)phosphonate 12 , respectively. Propyne iminium salt 1b reacts with Me 3 Si−PPh 2 to form (3‐morpholino‐1,3‐butadienyl)phosphane oxide 8 . The bis(donor)‐substituted allene 4 is transformed by oxidation of the phosphorus substituent into the push‐pull substituted allenylphosphane oxide 11 . Treatment of allene 4 with elemental sulfur results in the formation of betaine 16 , which undergoes [3+2] cycloaddition reactions with acetylenic esters to afford 5‐benzylidene‐4,5‐dihydrothiophenes 17 and 18 . (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)