68486-94-2Relevant academic research and scientific papers
REACTIONS OF 2-LITHIO-1,3-BENZODITHIOLE WITH CARBON DISULFIDE: FORTH AND BACK PROCESSES
Gimbert, Yves,Moradpour, Alec,Bittner, Shmuel,Jordis, Ulrich
, p. 819 - 822 (1989)
Carbophilic reaction of 2-lithio-1,3-benzodithiole with CS2, followed by the addition of a second base equivalent and quenching with MeI, yields 2--1,3-benzodithiole.An unexpected pathway mediated by MeS- and leading to the reformation of the 1,3-benzodithiole anion is described.
Enzymatic Cross-Benzoin-Type Condensation of Aliphatic Aldehydes: Enantioselective Synthesis of 1-Alkyl-1-hydroxypropan-2-ones and 1-Alkyl-1-hydroxybutan-2-ones
Di Carmine, Graziano,Bortolini, Olga,Massi, Alessandro,Müller, Michael,Bernacchia, Giovanni,Fantin, Giancarlo,Ragno, Daniele,Giovannini, Pier Paolo
supporting information, p. 4132 - 4141 (2018/09/12)
Benzoin-type reactions have been intensively exploited as a synthetic strategy for the preparation of α-hydroxy ketones. Thiamine diphosphate (ThDP) dependent enzymes are excellent catalysts for asymmetric versions of such reaction types. In particular, in cross-benzoin condensations of aromatic reactants and mixed aromatic/aliphatic reactions, use of these enzymes has resulted in high levels of chemo-, regio- and stereoselectivity. The present work, which confirms this trend for aliphatic reactants, outlines results obtained in the formal cross-benzoin-type condensation of the ‘umpoled’ acetaldehyde and propionaldehyde with various aliphatic aldehydes catalyzed by the ThDP-dependent enzyme acetoin:dichlorophenolindophenol oxidoreductase (Ao:DCPIP OR). In these reactions, 3-hydroxy-3-methylbutan-2-one (methylacetoin) was used as the activated acetaldehyde donor, while 4-hydroxy-4-methylhexan-3-one was employed for the first time as the precursor of activated propionaldehyde. With the exception of 3-hydroxypentan-2-one and 3-hydroxyhexan-2-one, which were obtained in almost racemic form by the condensation of methylacetoin with propanal and butanal, respectively, all other products achieved from reactions performed using the same donor with more hindered aldehyde acceptors were obtained with high conversions (89–99%) and in good to high enantiomeric excess (72–99% ee). In a similar way, high conversions (75–99%) and good ee (76–99%) were observed in reactions performed with the same set of aldehyde acceptors, but using 4-hydroxy-4-methylhexan-3-one as propionyl anion donor. This is the first time that most of the products described herein have been prepared via benzoin-type condensation. (Figure presented.).
Synthesis, Separation and Absolute Configuration Assignment to Enantiomers of 1,3-Benzodithiole 1-Oxide and 2-Alkyl-1,3-Benzodithiole 1-Oxides
Boyd, Derek R.,Sharma, Narain D.,Dorman, James H.,Dunlop, Robert,Malone, John F.,et al.
, p. 1105 - 1110 (2007/10/02)
1,3-Benzodithiole 1-oxide, 5, has been resolved into enantiomers using chiral stationary phase high performance liquid chromatography.Alkylation of an excess (25percent) of the late eluting (+)-(1R) enantiomer of the sulfoxide 5 under basic conditions yielded both cis and trans isomers of 2-methyl (6cis-1R,2S,6trans-1R,2R), 2-ethyl (7cis-1R,2S, 7trans-1R,2R) and 2-isopropyl (8cis-1R,2S, 8trans-1R,2R)-benzodithiole 1-oxide (25percent e.e.) and allowed a stereochemically correlation of absolute configuration between the suloxides 5 - 8. Treatment of racemic 1,3-benzodithiole 1-oxide (51S/51R) with potassium bis(trimethylsilyl)amide and (S)-(+)-1-iodo-2-methylbutane yielded four diastereoisomers of 2-(2'-methylbutyl)-1,3-benzodithiole 1-oxide (9cis-1R,2S,2'S, 9cis-1S,2R,2'S, 9trans-1S,2S,2'S, 9trans-1R,2R,2'S) which were separated by chiral stationary phase HPLC (CSP-HPLC).The most strongly retained diastereoisomer was analysed by X-ray crystallography and was assigned the (1S:1S:2'S) absolute configuration.Further alkylation of 9trans-1S,2S,2'S under similar conditions yielded 2-(2'S-methylbutyl)-2-(2"S-methylbutyl)-1,3-benzodithiole 1-oxide 10 of (1S,2'S,2"S) configuration exclusively.The same stereoisomer of the sulfoxide 10 was also obtained by dialkylation of the early eluting (-)-enantiomer of 1,3-benzodithiole 1-oxide (51S) using (+)-1-iodo-2-metrhylbutane, thus enabling the unequivocal establishment of the absolute configurations of the enantiomers of 1,3-benzodithiole 1-oxides listed in Table 1.A comparison of circular dichroism (CD) spectra for sulfoxides 5 - 9 indicates that this method may also be used to correlate absolute configurations of 2-alkyl substituted 1,3-benzodithiole 1-oxides.
