2-Hydroxy-2-methyltetrahydrofuran

Hydrogenation of ethyl 2,4-dioxopentanoate with an (S)-MeO-BIPHEP-Ru complex followed by in situ cyclization gives (3R,5S)-3-hydroxy-5-methyltetrahydrofuran-2-one with 98% ee and the 3R,5R isomer with 87% ee in an 84 16 ratio [236]. Ethyl 2-hydroxy-4-oxopentanoate is the only detectable intermediate. 1,3-Diphenyl-l,3-propanediol with a BIPHEMP-Ru complex is transformed to an anti-diol selectively [237]. 1,5-Dichloro-2,4-pentanediol, a versatile chiral building block, is selectively obtained through the BINAP-Ru catalyzed hydrogenation of a... 

Mori K. and Puapoomchareon P. (1987) Conversion of the enantiomers of sulcatol (6-methyl-5-hepten-2-ol) to the enantiomers of pityol [fra s-2-(l-hydroxy-1-methylethyl)-5-methyltetrahydrofuran], a male-specific attractant of the bark beetle Pityophthorus pityographus. Liebigs Annalen der Chemie 3, 271-272. 

The sequential 1,2 4,6 rearrangement of 6-benzoyloxy-3-methylcyclohex-2-enol (1, R1 = CH3) and 2,2-diethoxy-4-methyltetrahydrofuran (Table 22, entry 4) and Eschenmoser rearrangement of 4b has been utilized in the synthesis of optically active l/ -[(R)-2-hydroxy-l-methylethyl]-7a/ -methyl-l, 2,3aa,6,7,7a/f-hexahydroindene (6), an intermediate in the syntheses of vitamin D2 and 25-hydroxyvitamin D35155. 

A similar methodology was applied to the DKR of functionalised y-hydroxy amides by using Shvo s ruthenium catalyst in combination with immobilised Pseudomonas cepacia lipase (PS-C). This enzyme tolerated both variations in the chain length and different functionahties, giving fair to high enantioselectivities, as shown in Scheme 4.19. The synthetic utility of this procedure was illustrated by the practical synthesis of the versatile intermediate y-lactone, (R)- 5-methyltetrahydrofuran-2-one. 

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