Novel intermediates for the synthesis of carbocyclic spiro compounds

✍ Scribed by Vasu Nair; Tamera S. Jahnke

• Publisher: Elsevier Science
• Year: 1984
• Tongue: French
• Weight: 202 KB
• Volume: 25
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(01)91072-x

✦ Synopsis

Cyclic dienaminones, synthesized from the a-carbon elongation reaction of cyclic ketones with vinamidinium salts, are useful synthetic intermediates to carbocyclic Spiro compounds. The list of naturally occurring carbocyclic Spiro compounds continues to grow, and as it does, the need for useful intermediates for their syntheses also grows.1 This report will show that dienaminones of cyclic ketones l_ may act as synthetic precursors to highlyfunctionalized Spiro compounds via thermal or photochemical [4+2] cycloadditions. AH, 'CH, The dienaminones were synthesized by the reaction of 1,1,5,5-tetramethyl-1,5_diazapentadienium chloride 2 with a metal enolate. A wide variety of such dienaminones have been synthesized in our Laboratory. 3-5 An example is the reaction of the metal enolate of cyclopentanone with 2 which gave the dienaminone 3 in 5 90% isolated yield. The conversion is stereospecific and the sole product is the E,E (s-trans) isomer 3 as evidenced by 'H and 13C NMR data.

This was found to be true for all dienaminones formed from cyclic ketones.