272-35-5Relevant articles and documents
Toward Novel Antioxidants: Preparation of Dihydrotellurophenes and Selenophenes by Alkyltelluride-Mediated Tandem SRN1/SHi Reactions
Engman, Lars,Laws, Melissa J.,Malmstroem, Jonas,Schiesser, Carl H.,Zugaro, Lisa M.
, p. 6764 - 6770 (2007/10/03)
Reaction of 1-(2-iodophenyl)-1-methyloxirane (12) with 2 equiv of sodium n-butyltellurolate (n-BuTeNa), generated by the sodium borohydride reduction of di-n-butyl ditelluride, in THF, affords 2,3-dihydro-3-hydroxy-3-methylbenzo[b]tellurophene (13) in 62% yield, together with a small quantity of 1-(n-butyltelluro)-2-phenyl-2-propanol (27). This transformation presumably involves a tandem SRN1/SHi sequence. Similar reactions of 1-(benzylseleno)-2-phenyl-2-propanol (5a, R = Me) and 1-allyloxy-2-iodobenzene (15) afforded 2,3-dihydro-3-hydroxy-3-methylbenzo[b]selenophene (17, 74%), and 3-(n-butyltelluro)methyl-2,3-dihydrobenzo[b]furan (18, 50%), respectively. Lithium alkyltellurolates, generated by direct tellurium insertion into the required alkyllithium, or sec-butyl or tert-butyl substitution on tellurium provide product distributions similar to those observed for reactions involving n-BuTeNa. Lithium or sodium phenyltellurolate returned only starting materials from these reaction mixtures. The 2-[2-(n-butyltelluro)-1-hydroxy-1-methyl]ethylphenyl radical (14) is estimated to cyclize with kc 5 × 108 s-1 at 25 °C. The tandem SRN1/SHi sequence has been applied to the preparation of the antioxidant analogues, 5-hydroxy-2,3-dihydrobenzo[b]- tellurophene and selenophene (31, 32).
Synthesis of 1-benzometalloles containing group 14, 15, and 16 heavier elements via a common dilithiostyrene intermediate
Kurita,Ishii,Yasuike,Tsuchiya
, p. 1437 - 1441 (2007/10/02)
The Group 14 (Si, Ge, and Sn), Group 15 (P, As, Sb, and Bi), and Group 16 (Se and Te) 2-trimethylsilyl-1-benzometalloles (7) were prepared by the reaction of the corresponding metal reagents with β,o-dilithio-β-trimethyl- silylstyrene intermediate (6), which was derived from phenylacetylene or o- bromoiodobenzene via three steps. The trimethylsilyl group in 7 could be readily removed by treatment with tetrabutylammonium fluoride to give the C- unsubstituted 1-benzometalloles (10).
Dimetallation of phenylacetylene. Synthesis of ortho-susbtituted derivatives of phenylacetylene, benzoselenophene and benzotellurophene
Brandsma, L.,Hommes, H.,Verkruijsse, H. D.,Jong, R. L. P. de
, p. 226 - 230 (2007/10/02)
Phenylacetylene can be dimetallated in two ways. o-K-C6H4-CC-Li is formed by treating phenylacetylene at -70 deg C with two equivalents of butyllithium and one equivalent of potassium tert-butoxide in a mixture of tetrahydrofuran and hexane.The dimetallation with BuLi*N,N,N',N'-tetramethylethanediamine (TMEDA) affords a mixture of about 15percent (m + p)-Li-C6H4-CCLi and 85percent o-LiC6H4-CC-Li.Ortho-K-C6H4-CC-Li can be transformed into the dilithio or di-Grignard derivatives by addition of anhydrous lithium bromide or magnesium bromide etherate.Reaction of the dilithio derivative with elemental selenium and tellurium, followed by successive addition of tert-butyl alcohol and hexamethylphosphoric triamide (HMPT), gives benzoselenophene and benzotellurophene in good yields.Regiospecific functionalization of the nucleus via dimetal derivatives succeeds in the case of alkylation, halogenation, sulfenylation and acylation (with dimethylformamide and dimethylacetamide).Trimethylchlorosilane, chloromethyl methyl ether, aldehydes and ketones do not however react regiospecifically.
