Catalytic cyclometallation in steroid chemistry IV: Efficient method for the synthesis of tetrahydrothiophene, tetrahydroselenophen and cyclopentanone derivatives of (5α)-cholestane

• For the first time catalytic cycloalumination of (3β,5α)-3-vinylcholestane and (3α,5α)-3-allylcholestane were accomplished.
• Efficient syntheses of novel steroidal cyclic organoaluminum compounds.
• A convenient one-pot method for cyclopentanone and S,Se-heterocycle moiety formation on steroid.
• The structures of all novel compounds were confirmed by NMR measurements.

Catalytic cycloalumination of (3β,5α)-3-vinylcholestane and (3α,5α)-3-allylcholestane with Et3Al catalyzed by Cp2ZrCl2 was performed for the first time to give previously unknown aluminacyclopentanes in ∼90% yield; these products were converted in situ to carbo- and heterocyclic (5α)-cholestane derivatives.

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