References
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- Pennanen , S. I. 1977 . Tetrahedron Lett. , : 2631
- Hudrlik , P. F. and Withers , G. P. 1976 . Tetrahedron Lett. , : 29 and references therein
- Clive , L. J. C. 1978 . Tetrahedron , 34 : 1132