Reactivity of (bicyclo[5.1.0]octadienyl)iron(1+) cations: application to the synthesis of cis-2-(2'-carboxycyclopropyl)glycines.
The addition of carbon and heteroatom nucleophiles to (bicyclo[5.1.0]octadienyl)Fe(CO)(2)L(+) cations 5 or 8 (L = CO, PPh(3)) generally proceeds via attack at the dienyl terminus on the face of the ligand opposite to iron to generate 6-substituted (bicyclo[5.1.0]octa-2,4-diene)iron complexes (11 or 13). In certain cases, these products are unstable with respect to elimination of a proton and the nucleophilic substituent to afford (cyclooctatetraene)Fe(CO)(2)L (4 or 7). Decomplexation of 13f, arising from addition of phthalimide to 8, gave N-(bicyclo[5.1.0]octa-3,5-dien-2-yl)phthalimide (19). Oxidative cleavage of 19 (RuCl(3)/NaIO(4)) followed by esterification gave the cyclopropane diester 22, which upon hydrolysis gave cis-2-(2'-carboxycyclopropyl)glycine (CCG-III, 18) (eight steps from 4, 43% overall yield). This methodology was also utilized for preparation of stereospecifically deuterated CCG-III (d-18) and optically enriched (-)-18. Deprotonation of 22 resulted in cyclopropane ring opening to afford the benzoindolizidine (23).
Wallock
Nathaniel J
NJ
Department of Chemistry, Marquette University, P.O. Box 1881, Milwaukee, Wisconsin 53201-1881, USA.
Donaldson
William A
WA
D001643:Bridged Bicyclo Compounds / Q000737:chemistry*; D002264:Carboxylic Acids / Q000737:chemistry*; D002412:Cations; D003500:Cyclization; D003521:Cyclopropanes / Q000737:chemistry*; D005998:Glycine / Q000031:analogs & derivatives* / Q000138:chemical synthesis; D007212:Indolizines / Q000737:chemistry; D007501:Iron / Q000737:chemistry*; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry*; D010084:Oxidation-Reduction; D013237:Stereoisomerism; D014753:Vinyl Compounds / Q000737:chemistry*
D001643:Bridged Bicyclo Compounds; D002264:Carboxylic Acids; D002412:Cations; D003521:Cyclopropanes; D007212:Indolizines; D009942:Organometallic Compounds; D014753:Vinyl Compounds; C030797:cyclopropane; D007501:Iron; D005998:Glycine