Allylic PMB ethers rearranged in the presence of zeolite β to form 4-arylbutanals or 5-arylpentanones depending on the substituent pattern of the allylic moiety. Best results were obtained with substrates carrying simple substituents in the allylic 2-position, but a couple of substrates lacking a 2-substituent also rearranged. More functionalized substituents in this position were not tolerated. A propargyl PMB ether and a homoallylic PMB ether rearranged as well, but the products were mixtures of isomeric olefins. The 4-arylbutanals 2c and 2e and the 5-arylpentanone 2j were cyclized in PPA to give naphthalene and dihydronaphthalene derivatives, respectively.
Abstract The ring‐opening rates of some substituted 3‐thienyllithium derivatives have been measured and the activation parameters calculated for the ring‐opening of 2,5‐dimethyl‐3‐thienyllithium. Steric and electronic effects are discussed. J. Chem. Soc. , 14, 1085 (1977)
Two macrocyclic peptides 3 and 4 were formed during lactamization of 1,1'-ferrocenylbis(alanine) 1. Isolation, structure determination, and conformational analysis of 3 and 4 are reported as well as a controlled stepwise synthesis of 4 also including an improved route to 1. On the basis of their (1)H NMR spectra recorded at 300 K in DMSO-d(6), the dimer 3 and trimer 4 were found to be C(2) and C(3) symmetric, respectively. As appeared from computational analysis, the low-energy conformations of the macrocyclic peptides were nonsymmetric. Cyclic voltammetry revealed that the ferrocenyl moieties in 3 or 4 are electrochemically equal to ferrocene.
A method for the synthesis of novel fused tricyclic tetrazoles from allylic bromides generated by the recently discovered DiazAll reaction has been developed. This new tandem reaction comprises a cycloaddition between a nitrile and (TMS)N(3) followed by an intramolecular N-allylation. The variation of functionalities in the benzene moiety was well-tolerated, and only a moderate difference in yield and degree of purity was noticed. An exo-methylene group in these new compounds permitted further derivatization. Structural resemblance with substances which possess important pharmacological properties motivated the synthesis of a series of ketones and a small library of amines.
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