Steroidal O-tetrahydropyran-2-yl derivatives

Steroidal O-tetrahydropyran-2-yl derivatives, Ott et al. prepared the 0-tetra-hydropyran-2-yl derivative of testosterone by the reaction of testosterone with 2,3-dihydropyrane catalyzed by p-toluenesulfonic acid monohydrate. The reaction required three weeks and the yield was 59 %. Use of boron trifluoride etherate as catalyst raises the yield to 67% and lowers the reaction time to 10 hr. ... 

Some BFg-etherate added to a soln. of 3y -hydroxy-20-oxopregn-5-ene and 3-4 moles 2,3-dihydropyran in 4 1 ether-petroleum ether, and stirred 0.5 hr. at room temp. product. Y 76%. - BFg-etherate is a superior catalyst for effecting rapid formation of steroidal O-tetrahydropyran-2-yl derivs. in good yield. F. e. s. H. Alper and L. Dinkes, Synthesis 2972, 81. 

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See also in sourсe #XX -- [ ]

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