BF3-mediated reaction of a sulphone with aldehydes

Achmatowicz, Barbara; Baranowska, E.; Daniewski, A. R.; Pankowski, J.; Wicha, J.

doi:10.1016/s0040-4020(01)86203-7

Cited by 49 publications

(11 citation statements)

References 24 publications

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“…Under these conditions, the C¼C bond was not affected by the oxidant, and the expected products were obtained in satisfactory overall yields. Subsequent condensation of each of the sulfones 24a -24c with O-TBS ((t-Bu)Me 2 Si)-protected (S)-2-hydroxypropanal 25 [28] proceeded smoothly and did not require Lewis acid activation [29], contrary to the original procedure developed by Wicha and co-workers for the coupling of lithiated sulfones with protected hydroxy aldehydes [30]. The resulting hydroxy sulfones 26a -26c were obtained as mixtures of stereoisomers, which were immediately exposed to 20% Na/Hg alloy to deliver the desired O-TBS-protected (6S,9S)-a-ionols 27a -27c in ca.…”

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confidence: 83%

Enantioselective Synthesis and Olfactory Evaluation of 13‐Alkyl‐Substituted α‐Ionones

Luparia

Boschetti

Piccinini

et al. 2008

Chemistry & Biodiversity

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To study the influence of the steric bulk of the substituents at C(5) on the olfactory characteristics of alpha-ionone, the (S)-antipodes of compounds 8-10 were synthesized starting from (S)-alpha-cyclogeraniol (14a). The latter was available in useful preparative yield with 95% ee by enantioselective lipase-PS-mediated acetylation of the racemic mixture. Key step in the conversion of 14a to 8-10 was an S(N)2'-type reaction of an organocuprate on the allylic phosphate 20, which appears to be a general method for the introduction of an alkyl substituent at the cyclohexene C=C bond of ionones. Olfactory evaluation showed that, compared to the parent (S)-alpha-ionone (1), the odor strength and fragrance facets of the three analogues 8-10 are significantly influenced by the bulkiness of the substituent at C(13), giving further evidence that hydrophobic interactions of this group play a significant role in the chemoreception of ionones. In particular, the odor of the ethyl derivative 8 was found to be significantly stronger than that of the parent (S)-alpha-ionone (1).

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confidence: 83%

Enantioselective Synthesis and Olfactory Evaluation of 13‐Alkyl‐Substituted α‐Ionones

Luparia

Boschetti

Piccinini

et al. 2008

Chemistry & Biodiversity

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“…For instance, varying the nature of the counter ion can efficiently shift this unfavorable equilibrium. Thus, replacing lithium by magnesium [30][31][32][33][34][35][36][37] or the use of a lithiated sulfone/boron trifluoride combination [38][39][40][41][42][43] have proved to be effective. In Scheme 3.11, reaction 3.11 shows the beneficial use of magnesium salts in the Julia coupling employed as a key step in the synthesis of 24-epi-26,26,26,27,27,27- Furthermore, trapping of the in situ generated alkoxide -usually with Ac 2 O, BzCl, MsCl or TMSCl -can be a method of choice to shift the equilibrium in favor of the desired addition product.…”

Section: Preparation Of 12-disubstituted Olefinsmentioning

confidence: 99%

The Julia Reaction

Dumeunier

Markó

2003

Modern Carbonyl Olefination

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“…As outlined in Scheme 1, the synthetic strategy consists of the stepwise construction of the E-olefin in the w side-chain instead of the one-step Julia coupling, 7 because the starting aldehyde 6 is unstable under strongly basic conditions. 8 Thus aldehyde 6 9 was condensed with (formylmethylene)triphenylphosphorane in benzene at 80 °C to give (E)-a,bunsaturated aldehyde 7 in 64% yield. Carbonyl reduction of 7 using NaBH 4 in MeOH, followed by methoxycarbonylation of the resulting allylic alcohol with CICO 2 Me in the presence of DMAP in CH 2 Cl 2 gave the allyl carbonate 8 in 91% overall yield.…”

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confidence: 99%