Application of Hemithio Ketene Acetals to the Synthesis of Spirocyclic Orthoesters

Abstract

Spirocyclic orthoesters have been synthesized by a method that employs a hemithiophenyl ketene acetal as an orthoester precursor. The orthoesters can be generated in good yields and under mild reaction conditions.

orthoesters - spiro compounds - synthesis - acetals - thioketene acetals

References

1a Kuo S. Vedananda TR. White JD. Tetrahedron Lett.  1987,  28:  3061 

1b Ban Y. Hara H. Wakamatsu T. J. Org. Chem.  1985,  50:  108 

1c Leahy JW. Liverton NJ. Noda I. Remiszewski SW. Smith AB. Zibuck R. J. Am. Chem. Soc.  1992,  114:  2995 

1d Ashworth P. Belagali SL. Casson S. Kocienski P. Marczak A. Tetrahedron  1991,  47:  9939 

2a Hemithioketene acetal 4 was synthesized using a published method: Brandsma L. Schleyer P. Verkruijsse HD. J. Organomet. Chem.  1987,  332:  99 

2b

The ¹³C NMR spectrum of hemithio orthoester 6 has characteristic resonance signal at δ = 109.7 ppm.

2c

Two ¹³C NMR resonance signals at δ = 169.7 and 171.6 ppm were observed.

3a Crich D. Ritchie TJ. Tetrahedron  1988,  44:  2319 

3b McClelland RA. Santry LJ. J. Am. Chem. Soc.  1983,  105:  3167 

3c Kaloustian MK. Khouri FF. J. Am. Chem. Soc.  1986,  108:  6683 

3d Fueno T. Kitano M. Okuyama T. J. Org. Chem.  1987,  52:  2657 

4 Hemithio ketene acetal 7 was synthesized using a published method: Boeckman R. K., Bruza K. J.; Tetrahedron; 1981, 37: 3997

5

Deactivated silica gel refers to silica gel that was first treated with Et₃N, and then washed with the desired eluent.