Stereoselektive Synthesen von Alkoholen, I. C  C‐Verknüpfende Synthese von Allylalkoholen aus Aldehyden und Ketonen

Abstract

Die Umwandlung von Aldehyden und Ketonen 2 in die um ein C‐Atom reicheren Allylalkohole 3 gelingt durch Umsetzung zu den Vinylsulfoxiden 7, deren Isomerisierung zu den Allylsulfoxiden 9 und nachfolgende [2,3]sigmatrope Umlagerung.

From Allylic Sulfoxides to Allylic Sulfenates: Fifty Years of a Never-Ending [2,3]-Sigmatropic Rearrangement

“…This was also studied for aryl cycloalkenyl methyl sulfoxides that underwent preferential rearrangement through the exo transition state with chirality transfers that ranged from 44% ee for cyclopentenyl derivative 43 affording 44 to >90% ee for more hindered derivatives such as 45 (that contains an internal thiophile) affording 46 (Scheme 9). 33,34 The diastereoselectivities of these rearrangements in cyclohexenyl methyl sulfoxides with an additional chiral center were also examined for diastereomers 47 and 48 (Scheme 9), which gave rise to allylic alcohols 49 and 50, respectively. 35,36 The selectivities found suggested an important preference for the formation of an axial alcohol that, in the case of 48, overrides the exo effect noted for these sulfoxides.…”

Synthesis and analysis of l‐octen‐3‐ol, the main flavour component of mushrooms

“…Recently, 1-octen-3-01 has been obtained by the condensation reaction of heptanal with methylosulfinylobenzene to the proper vinyl sulfoxide (compound I), which undergoes isomerization to allyl sulfoxide (compound 11) and through sigmatropic rearrangement [2.3], giving the proper allyl alcohol [7].…”

Isomerisation of Vinyl Sulfones for the Stereoselective Synthesis of Vinyl Azides

“…It should be noted that when EWG equals a sulfinyl group a subsequent 2,3-sigmatropic (Evans-Mislow) rearrangement of the allylic product, 3, can occur. [12] Following this vein, other synthetically useful tandem variants of the general process outlined in Scheme 1 have been reported in specific cases where, from intermediate 2, either the acid-base chemistry cannot occur, or a competing process can take place. [14] We became interested in the process outlined in Scheme 1 in relation to our work with vinyl sulfone cysteinyl protease inhibitors [15] and in the realisation that the isomerisation of a readily accessible alkene (e.g.…”

“…In the case of esters (EWG = CO 2 R'), strong non‐nucleophilic bases such as LHMDS and LDA are required . However, for sulfones (EWG = SO 2 R'),, sulfoxides (EWG = SOR') and phosphate esters [EWG = PO(OR') 2 ], weaker bases, such as t BuOK and DBU, may be used. It should be noted that when EWG equals a sulfinyl group a subsequent 2,3‐sigmatropic (Evans‐Mislow) rearrangement of the allylic product, 3 , can occur .…”

“…However, for sulfones (EWG = SO 2 R'),, sulfoxides (EWG = SOR') and phosphate esters [EWG = PO(OR') 2 ], weaker bases, such as t BuOK and DBU, may be used. It should be noted that when EWG equals a sulfinyl group a subsequent 2,3‐sigmatropic (Evans‐Mislow) rearrangement of the allylic product, 3 , can occur . Following this vein, other synthetically useful tandem variants of the general process outlined in Scheme have been reported in specific cases where, from intermediate 2 , either the acid‐base chemistry cannot occur, or a competing process can take place …”