Jan Vader

The stereoselective syntheses of substituted furo[2,3b]furans.(part II)

Abstract Substituted furo[2,3b]furans, furo[2,3b]furan-2-ols and furo[2,3b]furan-2-ones were synthesized in a stereoselective manner. The key steps were the reactions of α-lithio-nitriles and dilithio-carboxylates with mono-substituted oxiranes.

Stereoselective syntheses of 2-subtituted perhydrofuro[2,3b]furans

Abstract New reagents for the stereoselective synthesis of 2-substituted perhydrofuro[2,3b]furanas are described. Ia the successful approach towards the latter compounds, the key steps were the addition of a aonolithio-2α-methoxy-3β-[(phenylsulfonyl)-methyilperhydrofuran to an aldehyde and a dilithio-2α-methoxy-3β-[(pheaylsulfonyl)-methyl]perhydrofuran to a carboxy1 derivative, respectively. The structures and conformations of the 2-tert-butylmtyl- and Z-isopropylper-hydrofuro [2,3b]furans were examined by means of 1H-NMR double resonance and the 2D-NOE spectroscopy.

The synthesis of a key intermediate in the total synthesis of insect antifeedant clerodanes

Abstract The synthesis of a key intermediate, 1,2,3,4,4a,5,6,7,8,8aβ-perhydro-4α-isopropyldimethylsilyloxy-4aα-isopropyldimethylsilyloxy-methyl-1α,2α-dimethyl-5-methylene-naphthalene-1β-carbaldehyde 31, in the total synthesis of insect antifeedant clerodanes is described. The stereochemistry of this intermediate is proven by an X-ray analysis of one of its precursors e.g. 10α-acetoxy-7β-(1,3-dioxolan-2-yl)-3,3aβ,4,5,6,6aβ,7,8,9,10-octahydro-7α,8α-dimethyl-1H-naphtho[1,8aα-c] furan 25. Crystal data: C19H30O5; monoclinic, P21/n, cell dimensions: a=7.9714(4), b=11.1722(4), c=19.7783(5) A, β=92.595(5) °, Z=4; conventional R-factor=0.053.

The conversion of a,b-unsaturated ketones into b-(phenylthio)-a,b-unsaturated ketones.

Abstract The oxidative functionalization of cyclic- and bicyclic-α,β-unsaturated ketones to β-(phenylthio)-α,β-unsaturated ketones was accomplished in high yields via addition of thiophenol followed by chlorination with chloreal and spontaneous elimination of hydrochloric acid.

Crystal and molecular structure of 7β-(1,3-dioxolan-2-yl)-3,3aβ,4,5,6,6aβ,7,8-octahydro-7α-methyl-8-oxo-1H-naptho[1,8aα-c]furan, C16H22O4

The structure of the title compound, C16H22O4, was determined by X-rays atT=290 K.Mr=264.320, triclinic, space groupP¯1,a=8.4857(9),b=10.0613(5),c=10.1499(7) Å,α=122.019(5)°,β=107.049(8)°,γ=74.892(9)°,Vc=696.5 Å3,Z=2,Dx=1.260 Mg m−3. MoKα radiation (graphite crystal monochromator,λ=0.70926 Å),μ(MoKα)=7.03 cm−1. Final conventionalR-factor=0.058,Rw=0.088 for 2223 unique reflections and 247 variables. The structure was solved usingMultan andDirdif. The alkylation step in the synthetic preparation of clerodane-like compounds results in an equatorial position of the dioxolan group.