LiAlH4, reaction with lactones

This methodology furnished also an efficient access into the furofuran skeleton, Scheme (19). A tandem Michael addition-aldol reaction was used to provide lactone 107 in 62% yield as a mixture of diastereomers in a ratio of 60 40. Dithiane 107 was converted into ketone 108 using HgO in combination with BF3 Et20. Subsequent reduction using an excess of LiAlH4 afforded tetraol 109 in 67% yield. The synthesis of (-)-eudesmin (110) was completed in 16% overall yield by dehydratation of 109 with BF3 Et20. 

---