Amidoalkylation in organic synthesis.1. Total synthesis of isoretronecanol and trachelanthamidine

The title compounds are prepared in five steps from N-2-bromo ethyl succinimide.     

Molecule‐Induced Peroxide Homolysis

The homolytic cleavage of peroxide bonds, leading to the formation of free radicals, plays an important role in the (spontaneous) oxidation of a wide variety of hydrocarbons in the presence of oxygen. Such aerobic oxidations can be desired (e.g. for industrially applied autoxidations) or undesired (e.g. food deterioration). In this contribution we provide experimental and computational evidence for a molecule‐induced homolytic dissociation mechanism between alkyl peroxide and compounds featuring weakly bonded H atoms such as (di)unsaturated hydrocarbons.     

s-Stable Laws in Insurance and Finance and Generalization to Nilpotent Lie Groups

s-stable laws on Hilbert spaces, associated with some nonlinear transformations, were introduced by Jurek.^{(16, 18)} Here, we interpret certain s-stable motions as limits of total amount of claims processes (up to a deterministic reserve) of a portfolio of (nontraded) excess-of-loss reinsurance contracts and show that they lead to Erlang's model. We also give explicit formulas for the price of perpetual American options in case the logarithm of the price of the underlying asset is an s-stable motion. Furthermore, we generalize the concept of s-stability to simply connected nilpotent Lie groups. For step 2-nilpotent Lie groups we characterize the Lévy measure and the s-domain of attraction of nongaussian s-stable convolution semigroups.     

Synthese von ‘Push-Pull’- Eninen

Synthesis of ‘Push-Pull’ Enynes ‘Push-pull’ enynes 1a–1f are easily available by Pd catalyzed coupling of stannyl-ynamines 15 and silylynamines 16 with β-iodo-enones 8 (Schemes 7 and 8).     

Versuche zur Synthese von ‘Push-Pull’-Diacetylenen

Attempted Synthesis of Push-Pull Diacetylenes Two alternative synthesis of push-pull diacetylenes of type 1 (5-amino-2,4-alkadiynals) are investigated. A bromination-dehydrobromination sequence starting with 5-dimethylamino-2,4-pentadienal ( 2 ) as well as the application of the well-known Cadiot-Chodkiewicz coupling reaction give new intermediates 3–5 , and 7 and 8 , respectively, but fail to give the target molecules 1 .     

Kupfer(II)-chlorid-katalysierte ‘Carben-Dimerisierung’ von 1-Halogeno-1-Lithiocyclopropanen: Ein einfacher Zugang zu Bi(cyclopropylidenen)

Copper(II)-Chloride Catalyzed ‘Carbene Dimerization’ of 1-Halogeno-1-lithiocyclopropanes: A Simple Access to Bi(cyclopropylidenes) A series of 13 bi(cyclopropylidenes) 11 are prepared in a simple one-pot reaction by halogeno-lithio exchange between 1,1-dibromocyclopropanes 1a – n and BuLi, in most cases at ?95°, to give 1-bromo-1-lithiocyclopropanes 2a – n , followed by treatment with CuCl₂ at low temperature and a simple workup at room temperature (Scheme 3c and Table 1). The yields of bi(cyclopropylidenes) 11 strongly depend on reaction parameters, as explicitly shown for the conversion 1f →→ 11f (Tables 2–8). Mixed couplings between two different carbenoids are possible (Scheme 4), while diastereoselectivity of the active transition-metal complex seems to be low. The structures of bi(cyclopropylidenes) 11 are confirmed by spectroscopic data as well as by X-ray analysis of an isolated crystalline diastereoisomer of 11k (Fig. 1).     

Oxidative Coupling of αω,-Di(cyclopentadienyl)alkane-diides

The Cu^II-induced oxidative coupling of αω,-di(cyclopentadienyl)alkane-diides 6 (n = 2–5) has been shown to proceed mainly by an intermolecular pathway to give polymers 8 , while the yield of intramolecular coupling 6 → 7 strongly decreases with increasing number n of C-atoms of the alkyl chain (Scheme 3). For n = 2, intramolecular coupling may be considerably enhanced by replacing the H-atoms of the CH₂CH₂ bridge of 6a (n = 2) by Me groups. In this case, intramolecular couplings 11 → 20 (Scheme 7) and 22 → 23 + 24 (Scheme 8) are accomplished with a total yield of 59% and 54%, respectively. All the intramolecular couplings investigated so far proceed stereoselectively to give the C₂-symmetrical cyclohexanes 7a, 20 and 23 with a fixed chair conformation. These results are easily explained, if a conformational equilibrium E ? F is operative in which large substituents R are assumed to enhance the gauche-conformation F which is the favored conformation for intramolecular couplings. Bridged dihydropentafulvalenes 20 and 23 are quantitatively rearranged to the thermodynamically favored bridged pentafulvenes 27 and 28 under base or acid catalysis, respectively (Scheme 9).     

Fulvene,VII. Analyse der 13C- und 1H-NMR.-Spektren

Carbon-13 and proton NMR. spectra of pentafulvene and of a series of 6-substituted fulvenes have been analysed and assigned by homo- and heteronuclear double resonance and with the aid of iterative computation. ¹³C and ¹H chemical shifts are interpreted in terms of substituent effects and compared with π-electron charges calculated for the unsubstituted fulvene. From ¹³C shifts a 10 percent contribution of dipolar structures to the electronic configuration of fulvene may be estimated. All long-range proton-proton coupling constants including relative signs and some proton-carbon couplings in the fulvene spin system have been determined and assigned.     

Synthese neuer Nonafulvene

Synthesis of New Nonafulvenes Nonafulvenes 1c and 1m – s are prepared by the following methods: (a) Elimination of AcOH from acetoxyalkyl-cyclononatetraenes (Scheme 2; 1m ); (b) alkylation of nonafulvenolates (Scheme 3; 1c , 1n ); (c) elimination of alcohol from di- and trialkoxymethyl-cyclononatetraenes (Scheme 5; 1o , 1p , 1q ); (d) deprotonation of intermediary formed formamidiniumcyclononatetraenes (Scheme 6; 1r , 1s ). Scope and limitations of these preparative sequences are discussed and compared with the corresponding pentafulvene syntheses.     

Eine neue Fulvensynthese. 4. Mitteilung

Fulvenes are prepared by condensation of sodium cyclopentadienide with x-acetoxy-x-chloro-hydrocarbon derivatives, followed by elimination of acetic acid with triethylamine. The yields are approximately 60% for 6-alkylfulvenes and similar to those of the classical synthesis for 6, 6-polymethylenefulvenes. The reaction is carried out at low temperatures and under water-free conditions. The purification of the fulvenes is simple.