Regiospecific and stereoselective carbometallation of alkynylsilanes by Ziegler-Natta alkylating agents

Silanes in organic synthesis. 10. Cleavage reactions of silylcyclopropanes with titanium tetrachloride and hydrogen chloride

“…Caled for C17H2602SSi: C, 63.31; , 8.13. Found: C,63.19;,8.09. 2-(Trimethylsilyl)bicyclo[2.2.2]octane (40). To a magnetically stirred suspension of 39 (323 mg, 1.00 mmol) and disodium hydrogen phosphate (570 mg, 4.0 mmol) in 10 mL of dry methanol cooled in an ice bath was added under nitrogen 1.50 g of 6% sodium amalgam.…”

Deacylation and deformylation of pyrroles

“…in a partial synthesis of dehydrocoproporphyrin (S-411 porphyrin). 4 In this paper we give full details of the deacy.lation process in pyrrole systems, modify it so that less obnoxious reagents are used, and extend the method to deformylation. The process of deacetylation is important in pyrrole synthetic chemistry since acetylpyrroles are readily available via standard ring fabrication routes,5,6 but unsubstituted pyrroles, in contrast, are not nearly so accessible.…”

“…Scheme I shows the results of attempts to deacetylate and deformylate pyrroles [1][2][3][4] with use of ethanedithiol and BF3 in acetic acid, and a general method is given in the Experimental Section. The 3-acetylpyrroles 1 and 2 were efficiently transformed, under these conditions, into the corresponding 3-unsubstituted pyrroles 5 and 6.…”

“…Likewise, the 3-formylpyrrole 3 was deformylated in 45% yield to give pyrrole 7. Attempts to deformylate the pyrrole 4 bearing three electron-withdrawing substituents were unsuccessful, and the corresponding acetal 8 was obtained in 64% yield.…”

“…Owing to the obnoxious nature of ethanedithiol, the deacetylations and deformylations were also attempted (4) Smith, K. M.; Langry, K. C. J. Org. Chem.…”