87921-58-2

Upstream product

• 87921-49-1 2-(1-bromo-2-propenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane 
• 100-52-7 benzaldehyde 
• 75-77-4 chloro-trimethyl-silane 
• 106-95-6 allyl bromide 
• 106-96-7 propargyl bromide 

Downstream Products

• 58927-85-8 (3Z)-1-phenyl-3-hexen-1-ol 
• 58927-86-9 (E)-1-Phenyl-3-hexen-1-ol 

Relevant academic research and scientific papers

Diastereo- and enantioselective synthesis of syn-α-vinylchlorohydrins and cis-vinylepoxides

A new method to generate chiral syn-vinylchlorohydrins and cis-vinyloxiranes is reported. Reaction of (α-haloallyl)lithiums with methoxy-9-BBN or Ipc2BOMe followed by treatment with BF3·OEt2 leads to (Z)-(γ-haloallyl)boranes which react with aldehydes to yield cis-vinylepoxides (de ≥ 90%) upon oxidative workup. Alternatively, addition of ethanolamine to the allylboration product yields syn-α-halohydrins (de ≥ 90%) that are also easily cyclized to cis-vinylepoxides. Extension of this protocol using [(Z)-γ-chloroallyl]BIpc2 leads to chiral syn-α-chlorohydrins and cis-vinylepoxides in high de (≥90%) and ee (90-99%). Enantioselectivity of reactions of chiral (Z)-(γ-chloroallyl)boranes with aldehydes are more sensitive to reaction conditions than enantioselectivity of reactions of other α-or γ-substituted allylboranes. The effects of proportion of BP3·OEt2 and the relative efficacies of LiNR2 bases on diastereo- and enantioselectivity of the chloroallylation are reported.

The hydroboration of propargyl bromide. Simple one-pot three-component routes to (Z)-1-bromoalk-1-en-4-ols and to anti-homoallylic alcohols

The hydroboration of propargyl bromide with dialkylboranes takes place regioselectively to give 3-bromoprop-1-en-1-yl dialkylboranes 13 which, upon quaternization with bromide ion, undergo a series of transformations into a number of allylic boron species. By a suitable choice of the experimental conditions it is possible to trap the reaction intermediates with aldehydes and to steer the process toward either the synthesis of (Z)-1-bromoalk-1-en-4-ols 6 or anti-homoallylic alcohols 8. Two one-pot three-component processes were developed based on a sequence of four reactions; preparation of dialkylborane and hydroboration of propargyl bromide are the first steps. Then, quaternization with TEBABr may be carried out either in the presence of the aldehyde when (Z)-1-bromoalk-1-en-4-ols 6 are requested, or in the absence of the aldehyde in order to allow the formation of γ-substituted allyl borane 18 which, successively, adds to the aldehyde affording antihomoallylic alcohols 8.

A one-pot three-component route to anti-homoallylic alcohols based on the hydroboration of propargyl bromide

(3-Bromoalken-1-yl)dialkylboranes, generated by hydroboration of propargyl bromide with dialkylboranes, smoothly rearranges to (E)-allylic boranes which can be trapped with aldehydes. The resulting one-pot three- component sequence represents a route to anti-homoallylic alcohols in fairly good yields.

Reactions of α-haloallyllithium derivatives with carbon, silicon, tin or boron halides and carbonyl compounds

A series of allylic halides have been converted into their α-carbanions with strong lithium bases, using different techniques.These have been compared in their reaction with various electrophiles leading to functionally substituted allyl derivatives.The influence of the counterion on the regio- and stereoselectivity has been investigated. allylic halides / α-halocarbanions / allylsilanes / allyltin derivatives / α-chlorohydrins / vinylepoxides / diastereoselectivity

Stereoselective Synthesis of Alcohols, XXII. E/Z-Selectivity on Addition of α-Substituted Allylboronates to Aldehydes

α-Heterosubstituted allylboronates 7 are prepared.Addition of 7 to aldehydes results in E/Z-isomeric homoallyl alcohols 13 and 14.The reasons for the predominant formation of the Z-isomer 14 are discussed.The Z-bromo olefins 16 and 20 obtained in this way serve as starting point for chain extension or formation of δ-lactones 21.

Z-SELECTIVE FORMATION OF SUBSTITUTED HOMOALLYL ALCOHOLS

The α-substituted allylboronates 4 add to aldehydes giving with high Z-preference the homoallyl alcohols 1.The Z-vinyl bromides obtained were further converted into δ-lactones.