Haruki Sashida

A Convenient One-Pot Preparation of Benzo[b]-tellurophenes,-selenophenes, and -thiophenes from o-Bromoethynylbenzenes

Abstract 2-Substituted and unsubstituted benzo[b]tellurophenes (3A a-e) were synthesized in one-pot from o-bromoethynylbenzenes (2) via three steps in good yields. Similarly, benzo[b]-selenophenes (3B a-e) and -thiophenes (3C a-e) were also obtained.

Tin-tellurium exchange reaction in tin-containing heterocycles: a new entry for the preparation of tellurium heterocycles

An alternative, simple and practical preparation of benzo[b]-tellurophene, 1H isotellurochromene, and 1-benzo- and 3-benzotellurepines by taking advantage of the tin-tellurium replacement reaction from the corresponding five-, six- and seven-membered tin-containing heterocycles was achieved.

Novel Oxidative Ring Opening Reaction of 1H-Isotelluro- chromenes to Bis(o-formylstyryl) Ditellurides

The oxidation of 1-unsubstituted or 1-phenyl-1H-isotellurochromenes with m‑chloroperbenzoic acid (mCPBA) in CHCl3 resulted in a ring opening reaction to produce as the sole products the corresponding o-formyl or benzoyl distyryl ditellurides, which were also produced by the hydrolysis of the 2-benzotelluropyrylium salts readily prepared from the parent isotellurochromene.

2-SUBSTITUTED ISOTELLUROCHROMENIUM SALT DERIVATIVES: PREPARATIONS, STRUCTURES, SPECTROSCOPIC PROPERTIES

Several types of novel isotellurochromenium salt derivatives (2-10) were prepared from the isotellurochromenes (1). The isotellurochromenium tetrafluoroborates (2), triflates (3-5), tosylates (6) and mesylates (7) are telluronium salts, and the dihalogenoisotellurochromenes (8-10) are telluranes. The molecular structures of the isotellurochromenium tosylate (6a) and the dichloroisotellurochromene (8a) were characterized by an X-ray crystallographic analysis using the 3-tert-butyl derivatives.

1-Allylation of 2-benzotelluropyrylium salts and 2-benzoselenopyrylium salts by means of allyltin reagents

3-tert-Butyl-2-benzotelluropyrylium salt (1) reacts with an equal amount of allyltributyltin to afford l-allyl-3-tert-butyl-1H-isotellurochromene (8a) in 93 % yield. Similarly, 1-allyl-1H-isotellurochromenes (9) and isoselenochromenes (10, 11) were prepared from the corresponding pyrylium salts (2-4) in moderate to good yields.

Studies on tellurium-containing heterocycles. Part 10. 1 2-Benzotelluropyrylium salts: first preparation and reactions with Grignard reagents

The first simple preparation of 2-benzotelluropyrylium salts 4 from o-ethynylbenzyl bromides 1 in two steps, and the characteristic reaction of these salts 4 with benzylmagnesium bromide and other Grignard reagents are described.

Studies on tellurium-containing heterocycles. Part 12.1 2-Substituted 1-benzotelluropyrylium salts: synthesis and reactions with nucleophiles

The general preparation of 2-substituted 1-benzotelluropyrylium salts 3 from the tellurochromen-4-ones 1 in two steps is outlined. The sensitive stability to the nature of the substituents at the C-2 position and the reactions with several nucleophiles including OMe–, diethylamine, CN–, an active methyl compound (acetone) and PhCH2MgBr, and also hydrogenation and hydrolysis reactions are described.

Synthesis of the first examples of 1-benzotellurepines and 1-benzoselenepines

The novel 2-alkyl-1-benzotellurepines 8 and 2-alkyl-1-benzoselenepines 9 have been obtained by sodium borohydride reduction of the ditelluride 4 and diselenide dimmers 5, prepared from 4-alkyl-1-(o-bromophenyl)but-1-en-3-ynes 3via three steps in one pot, together with the 2-methylene-tellurachromenes 10 and -selenachromenes 11, respectively, via the phenyl-selenol and -tellurol intermediates 6 and 7.

3-Benzotellurepines: the first examples of tellurepines

Reaction of o-diethynylbenzene with sodium telluride in the presence of hydrazine hydrate gives 3-benzotellurepine 2, which is converted into the 3,3-dihalogeno derivatives 3 by treatment with sulphuryl chloride or bromine; these compounds are the first examples of tellurepines.

Ruthenium Tetroxide Oxidation of N-Acyl Cyclic Amine-2-phosphonic Acid Diesters

The utility of the ruthenium tetroxide (RuO 4 ) oxidation of N-acyl cyclic amine-2-phosphonic acid esters was investigated. The oxidation of the N-protected cyclic amines (4, 5) having a phosphono diester group under the standard double layer condition of ethyl acetate-water using a catalytic amount of RuO 2 and excess NaIO 4 produce the corresponding lactams in good yields. The obtained lactam phosphono diesters (6, 7) were readily converted into the ω-amino-ω-phosphonocarboxylic acids (10, 11).