MCPB treatment of (±)-(1α,3α,3aβ,6aβ)-1,2,3,3a,4,6a-hexahydro-1,3-pentalenedimethanol and its O-acyl-protected derivatives; X-ray crystallography

Tănase, Constantin; Drăghici, Constantin; Cãproiu, Miron Teodor; Shova, Sergiu; Cojocaru, Ana; Munteanu, Cristian V. A.

doi:10.1016/j.tet.2015.04.096

Cited by 2 publications

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“…Retrosynthetic analysis of the key intermediates 5 and 6 ( Scheme 1 ), indicates that these compounds could be obtained by a sequence of two reactions: hydration of the double bond of alkene 1 to an alcohol, followed by the oxidation of the alcohol to the corresponding ketone. The starting compounds 1 were previously synthesized [ 25 ] and have already been used for the synthesis of “pseudocarbacyclin” type compounds [ 26 , 27 ], of the corresponding diols by hydroxylation with KMnO 4 [ 28 ], of the corresponding α and β-epoxides, by epoxidation of the double bond with MPBA [ 29 ], and of pentalenofuranic compounds by regioselective reactions [ 30 ]. Following our retrosynthetic analysis, we decided to hydrate the double bond of alkene 1 by hydroboration-oxidation with sodium acetoxyborohydride and with borane.…”

Section: Resultsmentioning

confidence: 99%

Hydroboration-Oxidation of (±)-(1α,3α,3aβ,6aβ) -1,2,3,3a,4,6a-Hexahydro-1,3-pentalenedimethanol and Its O-Protected Derivatives: Synthesis of New Compounds Useful for Obtaining (iso)Carbacyclin Analogues and X-ray Analysis of the Products

Tănase

Cocu

Cãproiu³

et al. 2017

Molecules

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Hydroboration-oxidation of 2α,4α-dimethanol-1β,5β-bicyclo[3.3.0]oct-6-en dibenzoate (1) gave alcohols 2 (symmetric) and 3 (unsymmetric) in ~60% yield, together with the monobenzoate diol 4a (37%), resulting from the reduction of the closer benzoate by the intermediate alkylborane. The corresponding alkene and dialdehyde gave only the triols 8 and 9 in ~1:1 ratio. By increasing the reaction time and the temperature, the isomerization of alkylboranes favours the un-symmetrical triol 9. The PDC oxidation of the alcohols gave cleanly the corresponding ketones 5 and 6 and the deprotection of the benzoate groups gave the symmetrical ketone 14, and the cyclic hemiketal 15, all in high yields. The ethylene ketals of the symmetrical ketones 11 and 13 were also obtained. The compounds 5, 6, 11, 13, 14 could be used for synthesis of new (iso)carbacyclin analogues. The structure of the compounds was established by NMR spectroscopy and confirmed by X-ray crystallography.

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Section: Resultsmentioning

confidence: 99%