Thiepines and fused derivatives

A number of thiepane stereoisomers were reported by Cere and coworkers 05JOC664 . Detailed vibrational circular dichroism spectroscopic and ab initio DFT studies were then undertaken and the absolute configuration of 102 was assigned (shown for the (+) enantiomer) 05JOC664 . 

Ring opening with reduction of dihydrodibenzothiepine (and the corresponding dihydrodinaphtho derivative) has been described utilising either 4,4 -di-ieri-butylbiphenyl-catalyzed lithiation or lithium naphthalenide at -78 °C in THF. With chiral dihydrodinaphthothiepine precursors, enantiomerically pure products were obtained 05T9082 . 

A review covering homologation of heterocycles via lithiation-based reductive ring opening, electrophilic substitution, and cyclization includes applications to 2,7-dihydro benzothiepine derivatives 06AHC135 . 

A neat synthesis of the chiral 10,ll-dibenzo[ / thiepine 79 from the chiral precursor 78 has been described. Cyclisation of the lithiated intermediate was mediated via reaction with sulfur W.v(i mid azole) 06OBC2218 . 

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There has been more activity with fused thiepines of various types. Ring-closing metathesis (RCM) of the sulfoxide 160 gave the fused thiepene oxide derivative 161 as a 1 2 mixture of the cis and trans isomers not unexpectedly, the thioether analogue of 160 did not cyclise under the RCM conditions due to chelation to the ruthenium centre in the catalyst [02SL1987],... 

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