Construction of cyclopentyl units by ring contraction reactions

Publisher Summary Twenty years ago, Walter Rudorff wrote a review for the series entitled “Graphite Intercalation Compounds” (R1). It was one of the four definitive articles to come out in 1959 and 1960 (HI, C1, U1), a period of intense activity in graphite research. One have now again reached the “fever pitch,” with not only the appearance of several new articles (E l , H2, W1), but also the convening of the first international conference dedicated exclusively to graphite compounds (H3 ). In the following, one shall concentrate on the work performed between 1974 and the present. The interlayer voids are frequently attacked to yield a periodic sequence of filled and empty spaces. The stage of a compound is defined as the ratio of host layers to guest layers, so that a first-stage compound, in which every interlayer void is filled, is the most concentrated. Historically, compounds of graphite have been placed in three categories, depending on the strength of interaction between the reacting species and graphite.

Graphite Intercalation Compounds

Publisher Summary This chapter discusses the most recent and important developments in the field of graphite and the structural properties and use of these compounds in organic and organometallic chemistry. Graphite has a lamellar structure, with an interlayer distance of 0.335 nm. Besides the large number of reagents that can be intercalated, a number of different types of graphites are used. The most commonly used potassium–graphite intercalation compound, C 8 K, shows an interlayer distance of 5.34 A, and all carbon layers are separated by a layer of K. Differences among the alkali metals in behavior toward graphite have been explained in terms of electron transfer. Pure yellow, first-stage compounds of Ba and Sr with graphite were prepared by the direct action of metal vapor on graphite in metallic tubes sealed under vacuum. C 8 K in toluene, benzene, or isopropylbenzene can act as an alkylation catalyst in the presence of ethylene to yield the corresponding nuclear and side chain-alkylated aromatic hydrocarbons. Graphite intercalation compounds can act as mild anionic polymerization initiators offering some benefits in comparison to analogous reactions in homogeneous medium or to metal dispersions.

Graphite metal compounds

Graphite intercalation compounds as reagents in organic synthesis. An overview and some recent applications

5.05 – Oxiranes and Oxirenes

New photoisomerization paths for epoxy-2,4-cyclohexadienones and a general mechanistic scheme for the photoisomerization of .alpha.,.beta.-unsaturated .gamma.,.delta.-epoxyketones

Synthetic used of alkali metals on charcoal and graphite: ketone alkylation

A new epoxyketone photorearrangement involving a cyclopropanone intermediate

The readily available benzodihydropentalene 6 and dimethyl acetylene-dicarboxylate react to give norbornadiene diester 8, with a three-carbon bridge from C1 to C2. Inrradiation of 8 gives the corresponding C1-C2 bridged quadricyclane diester 9, a new ring system. Diester 9 is quite stable, reverting to 8 with a t1/2 of 30 min at 170°C. The corresponding diacid 11, also prepared, reverts to its norbornadiene precursor at a considerably lower temperature, possibly as a consequence of acid catalysis.

Cheng-Tai Peng

Papers

New photoisomerization paths for epoxy-2,4-cyclohexadienones and a general mechanistic scheme for the photoisomerization of .alpha.,.beta.-unsaturated .gamma.,.delta.-epoxyketones

Synthetic used of alkali metals on charcoal and graphite: ketone alkylation

A new epoxyketone photorearrangement involving a cyclopropanone intermediate

1,2-Bridged Quadricyclanes

1,2-bridged quadricyclanes