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The first known lithiated 1-azafulvene derivatives, e.g., 8 and 13a, were generated by a low-temperature bromine–lithium exchange procedure with tert-butyllithium. These lithio species show substantial stability at ≤ −90 °C because, at these temperatures, the sterically demanding 6-diisopropylamino moiety, unlike the dimethylamino group, completely inhibits nucleophilic addition to C-6. At higher temperatures, the addition of tert-butyllithium to C-6 is significant and it can become the dominant process. The lithio species 8 is a useful formal equivalent of 5-lithiopyrrole-2-carboxaldehyde since, on reaction with electrophilic reagents and subsequent hydrolysis, a wide variety of regiochemically pure 5-substituted pyrrole-2-carboxaldehydes is formed. The 6-dialkylamino-1-azafulvenes described herein exist predominantly or exclusively as the syn conformer in solution at room temperature. This conformational preference is confirmed by a significance NOE effect between H-4 and H-6 in the parent diisopropylamino compound 3f. The origin of the syn conformational preference stems from a substantial contribution of the charge-separated form 16 to the ground state structure of these compounds, a phenomenon that is strongly supported by variable temperature NMR measurements on 2-bromo-6-diisopropylamino-1-azafulvene (3c). Keywords: 2-bromo-6-diisopropylamino-1-azafulvenes, stereochemistry, lithiation, pyrrole-2-carboxaldehydes.

The N,C-dilithiated derivatives of the N-tert-butoxycarbonyl-2-alkylthiomethylanilines 5a–c and the N-tert-butoxycarbonyl-2-alkoxycarbonylmethylanilines 11a, b were converted into the N-tert-butoxycarbonyl-oxindole-2-thiones(thiols) 7a–c and 14a, b, respectively, by sequential reaction with carbon disulfide and methyl iodide. Compound 7b was converted into 10d, the sulfur analog of MK886. Keywords: N-tert-butoxycarbonyl-2-alkylthiomethylanilines, dilithiation, N-tert-butoxycarbonyl-2-alkoxycarbonylmethylanilines, N-tert-butoxycarbonyloxindole-2-thiones.

Dimethylboron bromide or diphenylboron bromide can be used in combination with borane to achieve the regiocontrolled conversion of benzylidene acetals to their corresponding hydroxy benzyl ethers with moderate to high yields. Keywords: dimethylboron bromide, diphenylboron bromide, reductive opening, benzylidene, acetals.

Dimethylboron bromide or diphenylboron bromide can be used in combination with borane to achieve the regiocontrolled conversion of benzylidene acetals to their corresponding hydroxy benzyl ethers with moderate to high yields. Keywords: dimethylboron bromide, diphenylboron bromide, reductive opening, benzylidene, acetals.