Adolf Krebs

Synthese zweier germirene

Abstract The first isolable germirenes, 6a and 6b , were prepared by addition of dimethyl- and diethylgermylene, resp., to the seven-membered thiacycloalkyne 4 .

En route to tetra-t-butylethylene

Abstract Triene 22 was synthesized and converted by two different routes to the tetraaldehyde 27, the first “non-bridged” derivative of 1. An X-ray analysis of 27 reveals that the CC bond is twisted by 28.6°. Attempts to prepare 1 from 27 failed, thus far. Addition of t-butyllithium to 13, subsequent reaction with ethylene oxide and further reactions led to the highly strained tri-t-butylethylethylene 33; according to force field calculations 33 has the largest fragmentation strain of all synthesized hydrocarbons of this type.

Isolierbare cyclobutadiene, IV. - Reaktionen von singulett- und triplett-sauerstoff mit einem isolierbaren cyclobutadien. Eine dioxetan-dioxetan-umlagerung ☆

Zusammenfassung The reactions of the isolable cyclobutadiene 1 with 3O2 and 1O2 yield the 1,2-dioxetanes 2 and 3 in different ratios. The dioxetane 3 rearranges rapidly in polar solvents to the isomeric dioxetane 2.

Synthesis of a bicylic oxacycloalkenediyne system related to neocarzinostatin chromophore A

Abstract The synthesis of a stable bicyclic 12-membered oxacycloalkenediyne 2 related to the neocarzinostatin chromophore A 1 is described.

Synthese von verbrückten derivaten des tetra-tert. Butylethens

Abstract The sterically hindered alkenes 6 and 7 , which are potential precursors for the synthesis of tetra-tert.butylethene, were prepared. Attempts at the synthesis of 5 via the thiadiazoline route failed.

Tetra-tert-butylpyrazole and tetra-tert-butylthiophene

Abstract Tetra- tert .butylpyrazole ( 4 ) and tetra- tert .butylthiophene ( 11 ) were prepared starting from the seven membered cycloalkyne 1 and a reductive desulfurization in the last step. Some reactions of 4 and 11 are described. X-ray structural analyses of 11 and the corresponding S,S-dioxide were carried out.

A new route to 10-membered ring analogues of neocarzinostatin chromophore

Abstract The syntheses of new 10-membered cycloalkenediyne compounds related to neocarzinostatin chromophore 1 by intramolecular aldol type cyclizations are described.

[1+2]-cycloadditionen von isocyaniden an indiamine

Abstract Arylisocyanides and aroylisocyanides add to ynediamines in [1+2]- cycloaddition reactions to yield the corresponding cyclopropenonimines; electron withdrawing substituents in the arylisocyanides accelerate the rate of addition.

RADICAL IONS 561,2 ONE-ELECTRON OXIDATION OF 1,2-DITHIETE DERIVATIVES

Abstract Novel 1,2-dithiete derivatives R2C2S2 with R = [sbnd]C(CH3)3 and [sbnd]C(CH3)2[sbnd]CH2[sbnd]CH2[sbnd]CH2[sbnd]C(CH3)2[sbnd] are readily oxidized by the one-electron transfer system AlCl3/H2CCl2 to their radical cations. The single line ESR spectra, on high amplification, exhibit 33S satellites in natural abundance. Both the ESR data, i.e. rather large g values and 33S hyperfine coupling constants as well as MNDO closed and open shell calculations for the parent molecule H2C2S2 illustrate that spin and positive charge are predominantly located in the SS bridge of the four-membered ring.

Electron exchange chemiluminescence from a sterically stabilized cyclobutadiene-1,2-dioxetane

Abstract The rather stable 1,2-dioxetanes ( 2 ) and ( 3 ), derived from the sterically stabilized cyclobutadiene ( 1 ), exhibit distinct enhanced chemiluminescence behavior, namely energy transfer chemiluminescence (ETC) for ( 2 ) and electron exchange chemiluminescence (EEC) for ( 3 ).