Intramolecular reaction of β-(alkoxycarbonyl)allylsilane with epoxide into α-methylene-δ-lactones fused to carbocycles

Gas phase and condensed phase SNi reactions. The competitive six and seven centre cyclisations of the 5,6-epoxyhexoxide anion. A joint experimental and ab initio study. A comparison with SNi reactions of homologous epoxyalkoxide anions †

“…Peak widths at half height for the major peaks in these spectra are recorded in the legend to each figure. Data pertaining to product ion studies are listed in Table 3, and the mass spectra of two 18 O labelled derivatives are recorded in Table 4.…”

“…)1. 97 (19), 96(70), 95(100), 94 (8), 81(53), 79(66), 77(46), 69 (18), 67(39), 66(29), 65(25), 63 (11), 57(4), 55(8), 53 (13), 51 (15), 41 (22), 39(37), 31(4), 29 (6), 27 (11), 26(4).…”

“…, 68 (15), 67 (17), 66 (10), 65 (10), 57(2), 56 (8), 55(29), 53 (12), 51 (9), 50 (10), 43 (6), 41(43), 39(100), 29(76), 28(26), 27(64), 26 (18). The data considered to date show that 1 and 2 have identical fragmentations but do not indicate whether 1 cyclises to 2 before fragmentation occurs.…”

Synthesis and cytotoxic evaluation of β-alkyl or β-aryl-δ-methyl-α-methylene-δ-lactones. Comparison with the corresponding γ-lactones

“…1. Many methods of their preparation have been reported in the literature [24][25][26][27][28][29][30][31][32][33][34][35][36]. a-Methylene-d-lactones 2 also can act as Michael acceptors, therefore it is really surprising that the data about the cytotoxic activity of these compounds are scarce and no systematic SAR investigations have been undertaken so far.…”

Synthesis of spiro[4.5]decane and bicyclo[4.3.0]nonane ring systems by self-cyclization of (Z)- and (E)-2-(trimethylsilylmethyl)pentadienal derivative

“…6 Cyclopentane ring was also synthesized by the reaction with an enone. 7 Nishitani et al prepared g-and d-lactones by the reaction with either an aldehyde 8 or an epoxide, 9 respectively. Further conjugation of CvC double bond to this moiety enables self-cyclization to form a five-membered ring compound, and therefore, the reaction is not expected to be a simple extension.…”