Zdenko Majerski

Carbon-13 chemical shifts of inverted carbon atoms

Abstract The inverted carbons in 2,4-methano-2,4-dehydroadamantane are shielded by 14.3 ppm relative to the corresponding carbons in 2,4-methanoadamantane. This was explained by the balance of the inverted carbon hybridization deshielding, the shielding effect of the cyclopropane rings formed, and the change in the influence of the neighbouring atoms.

A Convenient Synthesis of 1,3-Divinyladamantane

Abstract 1,3-Divinyladamantane was prepared in 30% overall yield by LiAIH4 reduction of 1,3-bis (carboxymethyl) adamantane, conversion of the resulting diol to the borate ester, and pyrolysis of the ester in vacuo.

Hypoiodite thermolysis-cyclization route to polycyclic ketones. Direction of he CC-bond scission. Rearrangement of 6-potoadamantanol to 2- and 4-homobrendanone

Thermolysis of 6-protoadamantyl hypoiodite followed by intramolecular, base-promoted, cyclization of the resulting iodoketones yields 70% of a 3 : 2 mixture of -homobrendan-4-one and 2-homobrendan-2′-one. Direction of the ???CC bond scission in the hypoiodite appears to be conrolled by the relative strain energies of the iodoketones.

Thermolysis of 1-homoadamantyl hypoiodite. Convenient synthesis of 10-homoprotoadamantan-4-one (tricyclo [4.3.2.03,8]undecan-4-one)

Abstract Thermolysis of 1-homoadamantyl hypoiodite followed by intramolecular cyclizatlon yields 74% of the hitherto unknown 10-homo aprotoadamantan-4-one; the hypoiodite thermoIysis-cyclization sequence appears to be an excellent method for the preparation of adamantanoid ketones.

Hypoiodite thermolysis–cyclization reaction. Convenient synthesis of 4-homoprotoadamantan-4-one (tricyclo[5.3.1.03,9]undecan-4-one) from 3-homoadamantanol

Thermolysis of 3-homoadamantyl hypoiodite followed by base-promoted intramolecular cyclization yields 78% of a 3:2 mixture of 4-homoadamantanone and the hitherto unknown 4-homoprotoadamantan-4-one (tricyclo[5.3.1.03,9]undecan-4-one).

Intramolecular γ C–H insertion vs. olefin cycloaddition in 4-methylene-2-adamantylidene and 8-methylene-2-noradamantylidene

8-Methylene-2-noradamantylidene inserts readily into the γ C–H bond giving 6-methylene-2,4-didehydro-noradamantane rather than the olefin-cycloaddition product, while its higher homolouge 4-methylene-2-adamantylidene reacts exclusively by intramolecular cycloaddition to the olefinic bond yielding 2,4-methano-2,4-didehydroadamantane, a [3.1.1.]propellane.

Dehydroprotoadamantanes. Intramolecular insertion reactions of 4- and 5-protoadamantylidene

Pyrolyses of tosylhydrazone sodium salts of 4- and 5-protoadamantanone produced, in addition to protoadamantene, 2,4-dehydroadamantane and 5,7-dehydroprotoadamantane, respectively; the carbene appears to approach with its empty p-orbital towards the nearest C–H bond of suitable geometry to form the product.

The degenerate isomerization of adamantane

Treatment of specifically labelled [2-14C]adamantane with aluminium bromide in CS2 solution at 110° for 8 h leads to 78.4% of the total scrambling of carbon atoms possible on a statistical basis.

Synthesis of 9-substituted homoadamantanes

Abstract 9-Homoadamantanone was prepared conveniently from 1-homoadamantanol via 10-homop rotoadamantan-4-one in 58% overall yield.

The synthesis of 2,4-dehydrohomoadamantane

2,4-Dehydrohomoadamantane (IVa)†; was prepared by the pyrolysis of the sodium salt of 4-homoadamantyl tosylhydrazone (I); hydrogenolysis of (IVa) gave homoadamantane exclusively.