Four homoallyl ortho-vinylaryl ketones (10a-d) -1,8dienes of sorts -were prepared by several approaches. In the presence of 1-2 mol-% Grubbs-II catalyst, they ring-closed to give 6,7-dihydrobenzocyclohepten-5-ones (11a-d) in 90-96 % yield. With SeO 2 the parent compound (11a) delivered benzocyclohepten-5-one (13a) and/or selenium-containing compounds (18)(19)(20)(21)(22) but no more than traces of 6,7-benzotropolone (5a). However, 5a was accessible from compound 11a via the sodium enolate and allowing it to react with a stream of oxygen [a] Scheme 1. Top: our previously established ring-closing olefin metathesis ("RCM")/ketal hydrolysis route to type-5 6,7-benzotropolones. [9] Underneath: regiocomplementary processings of a type-4 RCM product via the dibromide 7 and the bromoolefins 7 or iso-7 by cross-couplings and hydrolyses giving type-8 or type-iso-8 6,7-benzotropolones, respectively. [10] The Arican routes of Scheme 1 have a major drawback, though, namely the harsh conditions required for hydrolyzing a type-4 ketal in the last step: Liberating the enol required refluxing with 10 equiv. of tosic acid and 100 equiv. of water in acetonitrile for 1 h -2 d. [9,10] These conditions were applicable to certain type-9 or type-iso-9-ketals, as well ( Figure 2). When their substituent R was Et, Ph, CO 2 Me or CO 2 Et, such hydrolyses also proceeded well. [9] However, when their substituent R was CH=CH-CO 2 iPr (in 9a or iso-9a), HC=CH 2 (in 9c or iso-9c) or C≡C-SiMe 3 (in iso-9c) the substrate vanished under hydrolysis conditions without delivering any benzotropolone. [9,10] The C≡C-SiMe 3 -containing ketal 9b was an in-between-case: Its hydrolysis released a benzotropolone as expected but the sidechain R had been converted into C(=O)-CH 3 . [10] Eur.2930 Scheme 2. Can 6,7-benzotropolones 5 be reached via an RCM/oxidation route rather than via the RCM/hydrolysis route of Scheme 1? A 4-e 2 oxidation 11 → 5 would be required overall, but two 2-e 2 oxidations 11 → 12 and 12 → 5 might be used as an alternative. 5.We wondered whether step 2 might be disadvantaged vs. a dehydration delivering the benzotropone 13. While 13 looks like a dead-end at first, it might be re-routable towards 5. This is because unsubstituted benzotropone (13, all R = H) gave unsubstituted benzotropolone (5, all R = H) by endoperoxide formation and an ensuing reduction with thiourea. [11] Consequently, benzotropones 13 appeared as conceivable intermediates of our Scheme-2 strategy towards benzotropolones. A Modified Synthesis of 6,7-BenzotropoloneOur proof-of-principle benzotropolone synthesis by the approach of Scheme 1 delivered the parent compound 5a and is shown in Scheme 3 and Scheme 5. Scheme 3 advances to the RCM product and Scheme 5 supplements its oxidation. Scheme 3. Reaching the RCM product 11a, our synthetic precursor of unsubstituted benzotropolone (5a).Our synthesis began by a salt-free Wittig methylidenation of ortho-bromobenzaldehyde (14, Scheme 3). [12] The resulting ortho-bromostyrene (15) was treated sucessively with nBuLi and the...

This work investigates the synthesis of bio‐based pressure‐sensitive adhesives and their characterization in terms of mechanical properties relevant to processing and application. The synthesis of monomers based on various fatty acids derived from vegetable oils as renewable feedstock via a one‐step, a two‐step, and a three‐step route is described. The resulting monomers are polymerized via free radical polymerization resulting in high molecular weight polymers with adhesive properties. Adhesives are also obtained as aqueous dispersions by means of miniemulsion polymerization. In particular, the monomer acrylated methyl oleate (4ac) and the thereof derived polymer are intensively studied. The synthesized homopolymers show characteristic mechanical and adhesive properties similar to conventional pressure sensitive adhesives.

A series of 1.1 -dichlorocyclopropanes containing various ring substituents has been prepared and the compounds have been pyrolysed in a flow system at 500-670".This pyrolysis is a useful route to olefins. 1,l -Dichlorocyclopropane gives 2,3-dichloropropene in high yield. Cyclopropanes containing more chlorine substituents also give, in each case, a high yield of a single olefin isomeric with the cyclopropane; for instance 1.1.2-trichlorocyclopropane gives 1,1,3-trichloropropene, the 1.1,2,2-tetrachloro-compound gives 1,1,2.3-tetrachIoropropene, and 1 ,I ,2-trichloro-2-chloromethylcyclopropane gives 1,1.3-trichloro-2-chloromethylpropene. Cyclopropanes which contain other substituents give mixtures of isomeric olefins. For instance 1.1 -dichloro-2-methylcyclopropane gives 2,3-dichlorobut-1 -ene and 1.2-dichlorobut-2-ene. The results are interpreted in terms of a unimolecular concerted chlorine-atom migration and ring-opening mechanism.

Front Cover: The synthesis of bio‐based pressure sensitive adhesives and their characterization in terms of mechanical properties relevant to processing and application is described. Renewable monomers are obtained from vegetable oils as a renewable feedstock and polymerized via free radical polymerization, resulting in high molecular weight polymers with mechanical and adhesive properties similar to conventional pressure sensitive adhesives. Further details can be found in the article by W. Maaßen, S. Oelmann, D. Peter, W. Oswald, N. Willenbacher,* and M. A. R. Meier* on page 1609.

Abstract:The kodaistatins A-D are strongly anti-diabetic natural products from Aspergillus terreus that hold some promise of an ovel diabetes cure. However,c onsiderations of that kindf ace two drawbacks: 1) The kodaistatins A-D contain ah eavily substituted pulvinone/cyclopentenone combination;2 )they are 1,2-diols, the 3D structures of which have not been assigned yet. However,w ec an exclude two of the four possible stereostructures. We conclude that kodaistatin Ai satrans-, not a cis-diol from NMR comparisons with ap air of cis, trans-isomerick odaistatin models, which we synthesized in 11 and 12 steps, respectively.T he stereocenters of the diol moiety arosefrom stereocomplementary,h ighly diastereoselective aldol additions of al ithium enolate or the corresponding silyl ketene acetal. The cyclopentenone moieties stemmed from intramolecular aldol additions and ensuingd ehydrations. The requisite enolates wereo btained by the reduction of a-bromoketones with samarium diiodide.