Dioxepines, dithiepines and fused derivatives

Fused cyclohexyl-1,2-dioxepines 141 and 142 were synthesised by the reaction of a peroxy hemiketal 140 onto a tethered a,(3-unsaturated ester. The reaction proceeded best when promoted by mercuric acetate 07T10407 . 

A sulfur-transfer reagent was used for the synthesis of 1,2-dithiepines 144, potential radiation-protection drugs, from the ditosyldisulfide 143 JOC2106 . 

The Heck reaction of 2-substituted-l,3-dioxepines 145 occurs with high diastereoselectivity to give trans substituted products 146 070L5099 . 4-Substituted derivatives also give trans products. 

5-Amino-l,3-dioxepines were synthesised as potential new non-steroidal antiinflammatory agents by the reaction of an aldehyde with the appropriate amino-diols 07BMC6273 while benzodioxepines related to the marine odorant Calon 1951 have been synthesised and the nature of substituents on olfactory character analysed 07HCA854, 07HCA1006 . 

A Hg(II)-catalysed rearrangement of P-hydroxy Mv-dithiane 147 gave 1,4-dithiepines 148 070L4061 , while the 1,4-dithiepines 149 were synthesised as scaffolds for medicinal chemistry in good yield by the three component coupling of ethanedithiol, malononitrile and an aromatic aldehyde 07JOC3443 . 

Lewis acid mediated [1,3] rearrangement of the 1,3-dioxepines 109 gave the trisubstituted tetrahydrofurans 110 in high yields and with generally high diastereoselectivities. The Lewis acids used included TiCf(7-PrO)2 and TBSOTf 06CC3119 . 

The catechol 153 has been used in an efficient 3-step synthesis via 154 of the perfumery component Calone 1951 , 7-methyl-benzo[6][l,4]dioxepin-3-one 156 05TL39 . The diester/ester intermediates 155 were converted to 156 in high yield in a short (4 min) microwave-assisted hydrolysis/decarboxylation sequence. 

Novel 7-membered ring based peroxides, including the spiro system 158 have been reported 05TL6801 . Compound 158 resulted from an intramolecular Michael-type addition on treatment of 157 with base. 

5-dihydro-2,5-methano-l,3-benzodioxepine together with a furo[2,3-Z)]benzofuran have been reported to arise on treatment of 5-hydroxy-3-methyl-3//-benzofuran-2-one with LiAlILt followed by acidification with oxalic acid 05JOC6171 . 

A series of novel, chiral (and racemic) 1,4-dioxepanofuranose nucleosides have been described. These are an interesting new class of bicyclic nucleoside derivatives 05CAR1081 . 

A novel 7-membered ring compormd, (-)-3,4-dihydro-3-hydroxy-7-methoxy-2//-l,5-benzodithiepine-6,9-dione has been isolated from the stems of the mangrove plant Bruguiera sexangula var. rhynchopetala 05HCA2757 . 

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Several reports describe reactions on the attached rings of benzo-fused dioxepins and dithiepins. For example, biphenyl derivative 79 was prepared in a two-step procedure by halogenation of 130 with NaBr/oxone in aqueous acetone and subsequent substitution of the 131 with a methoxy group (Scheme 34) <2006T635>. 

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