Silylene Transfer to Allylic Sulfides: Formation of Substituted Silacyclobutanes

Abstract

Silylene transfer to allylic sulfides results in a formal 1,2-sulfide migration. The rearrangement yields substituted silacyclobutanes, not the expected silacyclopropanes. The silacyclobutanes were elaborated by insertions of carbonyl compounds selectively into one carbon–silicon bond. A mechanism for the 1,2-sulfide migration is proposed involving an episulfonium ion intermediate.

Regioselective Benzoylation of Diols and Carbohydrates by Catalytic Amounts of Organobase

“…The yield of 2 increased with the amount of DBU used up to 0.4 equiv (Entries 12, 13 and 14). [15][16][17][18]. The addition of DMF is not necessary for diols due to their good solubility in acetonitrile.…”

“…More specifically, developing environment-friendly, convenient, efficient and highly regioselective carbohydrate protection methods remains as one of the most prominent challenges [9]. Over the last several decades, many protection methods have been developed, including the use of reagents such as organotin [10][11][12], organoboron [13,14], organosilicon [15][16][17], metal salts [18][19][20][21][22][23], organobase [24][25][26], and enzymes [27][28][29][30]. Although these reagents each have advantages, they also possess troublesome shortcomings including inherent toxicity, high cost and the necessity to pre-protect secondary hydroxyl groups.…”

Catalyst Free Selective Monobenzoylation of Diols with Benzoyl Cyanide: A Robust and Regioselective Strategy

“…General information, representative procedure, spectral data of all compounds (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17) and the copies of 1 H NMR and 13 C NMR are reported in supporting information.…”

“…We were delighted to observe that the quantitative yield of compound 3 was obtained when the temperature was adjusted to 35 o C and 2 mmoles of benzoyl chloride were used as a benzoylating agent (entry 12). With the increase in temperature up to 100 o C, the yield of product 3 decreased significantly (entry 13,14). It is to mention here that when benzoyl chloride was used as a benzoylating agent instead of benzoyl cyanide under similar reaction conditions, a di-benzoylated adduct, 4, was obtained as an exclusive product in quantitative yield (entry 15, Table 1).…”

“…Though many protocols for selective protection of hydroxyl groups have emerged in literature [1][2] but procedures that display high levels of substrate generality are still limited barring a few metal catalyzed methods [3][4][5][6] (Scheme 1). Over the years, the protection methods that have been developed include the use of catalysts such as organotin, [7][8][9] organoboron, [10][11] organosilicon, [12][13][14] metal salts, [15][16][17][18][19][20] organobases [21][22][23][24] and enzymes. [25][26][27][28] These catalyst driven reactions not only facilitate the protection of a particular hydroxyl group in polyols, but also realize natural product synthesis or therapeutic agent/s synthesis in a minimum number of steps.…”