Additions of aldehydes to metallated trans-1,3-Dithiane-S,S-dioxide under conditions of kinetic and thermodynamic control

Asymmetric Nucleophilic Acylation of Aldehydes via 1,1-Heterodisubstituted Alkenes

“…Purification was achieved by column chromatography (petroleum ether/ethyl acetate 13:1). The enantiomeric excess was determined by chiral GC: isothermal 100 8C, 24.27 min (2S), 25.20 min (2R); AD-mix a: ee (S) 12.1 %; AD-mix b: ee (R) 11 Dimethoxymethyldiphenylphosphine oxide (31) and diethoxymethyldiphenylphosphine oxide (32): p-Chlorodiphenylphosphine (1 equiv) was added dropwise (caution: exothermic) to freshly distilled trialkylorthoformiate (1 equiv) under nitrogen at RT. The reaction mixture solidified and was heated for 2 h at 110 8C, by which alkyl chloride was removed.…”

“…[10] Alternatively, when chiral formyl-anion equivalents are employed (reagent control) more stereochemical flexibility is gained because achiral aldehydes can be used and both stereochemical series become principally accessable. Typical examples for this strategy are the use of C 2 -symmetric trans-1,3-dithiane S,S-dioxides, [11] chiral O,S-acetals, [12] and amino cyanides {[R 1 C(NR* 2 )CN] À [M] } or formaldehyde SAMP-hydrazones. [13] Corey and Jones described a very different three step approach by utilizing a nucleophilic chiral alkinylmethyl borane in an addition reaction with aldehydes.…”

Rigid Orthogonal Bis-TEMPO Biradicals with Improved Solubility for Dynamic Nuclear Polarization

“…Compounds containing the 2,4,8,10-tetrathia[5.5]undecane skeleton have been previously reported but in general have been less studied than their oxygen counterparts. − Oxidation of the sulfur atoms to sulfoxides and sulfones was expected to introduce polar groups that promote solubility in polar solvents. Reports of oxidized 1,3-dithianes in the literature suggested that the compounds might have the desired solubility . We initially chose to synthesize the tetrasulfone version of 1 (Scheme ) because we anticipated that it would be easier to characterize as compared to the intermediate oxidation products.…”

Anion Reactions of 1,3-Dithiane 1,3-Dioxide with Carbonyl Compounds: High Diastereoselectivity with Aromatic Aldehydes under Conditions of Equilibrium Control

“…Lithiated naphthyl methyl sulfoxide 217 and the binaphthyl-based dithiepine 31819 show high diastereoselectivity with benzaldehyde. In our own studies, we have found that fmn.s-l,3-dithiane 1,3-dioxide ( 4) reacts with very high diastereoselectivity with aromatic aldehydes, [20][21][22] and in this paper we describe our results in full. The 1,3-dithiane 1,3-dioxide moiety can be readily converted to a thioester which in turn can be transformed into an acid, ester, amide, ketone, or aldehyde.…”