Supplementary Material Available. (1) The final atomic positions and temperature factors for isotetrahydroanemonin (15), and the final atomic positions and temperature factors for di-a-methyleneanemonin (4b) (Tables 1-4); (2) supplements to Tables I, II, VII, and VIII, which list the bond lengths and angles involving hydrogen atoms in 15 and 4b; (3) Tables IV, V, VI, VII, VIII, X, XI, XII, and XIII, which are mentioned in the text; and (4) Figures 2, 4, 5, and 6 mentioned in the text (15 pages). Ordering information is given on any current masthead page.

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Utilizing stable solutions of i-PrzNLi in hexane, a convenient procedure is described for the conversion of methyl w-bromoalkyl ketones 9-12,32,42,50, and 67 to mixtures of Li+ enolates containing predominantly the terminal enolates. Although solutions of these Li+ enolates in EtzO-hexane mixtures are stable a t 0 "C, when activating ligands such as 4 molar equiv of HMP [(MezN)sPO], 1 molar equiv of triglyme (15) or the 14-crown-4 ether 16, or excess DME are added these Li+ enolates undergo intramolecular cyclization reactions. In the absence of serious geometrical con!straints (cf. bromo ketone 32), the enolates of bromo ketones 9-12 underwent intramolecular C-alkylation to form the corresponding cyclohexanone derivatives in 60-80% yield. Similar intramolecular cyclization by bromo ketone 67 produced a mixture of five-membered and seven-membered C-alkylated products, but intramolecular cyclization of the bromo ketone 42 yielded only the five-membered 0-alkylated product 43. The Li+ enolate of bromo ketone 50 underwent a very slow intramolecular cyclization to produce a mixture of 0-alkylated and Calkylated four-membered ring products. Thus, the method described constitutes a useful synthetic route to cyclohexanone derivatives and, with limitations, is also applicable to the synthesis of cycloheptanone derivatives. n Br 5 i 7 0 1978 American Chemical Society Br 6 1 8 Metal Enolates from w-Bromo Ketones

Reaction of benzothiazole with dimethyl acetylenedicarboxylate in aqueous methanol gives irons-dimethyl 4formyl-2,3-dihydro-l,4-benzothiazine-2,3-dicarboxylate in high yield, and a mechanism is proposed for this novel transformation. The scope and limitations of the process have been defined by examination of the reactions of a wide range of substituted benzothiazoles with dimethyl acetylenedicarboxylate in aqueous methanol; the results are fully consistent with the postulated mechanism.

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