A menthol derived synthon for preparing homoallylic alcohols bearing three contiguous elements of stereochemistry and Progress towards a synthon with two centers of reactivity for the allylation of two different aldehydes Open Access

Ochs, Nellie Ann Kroeze (2014)

Permanent URL: https://etd.library.emory.edu/concern/etds/dz010q75w?locale=en
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Abstract

Homoallylic alcohols with α- and γ- functionality are prevalent in natural products and drug analogs and are valuable building blocks for the syntheses of these compounds. Allylic transfer reactions using organic allyl transfer agents have been developed to circumvent the complexity of synthesis and use of metal catalysis in allylboranes and carbonyl-ene reactions. These organic allyl transfer reactions with aldehydes undergo a 2-oxonia[3,3] sigmatropic rearrangement, proceeding through a pseudo-chair conformation transition state that dictates the stereochemistry of the product. We have synthesized two new synthons, the first for the formation of homoallylic alcohols bearing three contiguous elements of stereochemistry, and the second for the formation of 1,5-diols from two different aldehydes. The first synthon has successfully reacted to produce a homoallylic alcohol moiety in >99:1 dr and 2.1:1 er. The er of this reaction suggests that the reaction of the synthon with aldehydes may go through an open transition state instead of the sigmatropic rearrangement. Conditions for the synthesis and rearrangement with the second synthon are still being optimized. Future work will include the development of chiral aldehydes to react with these synthons and further work in complex synthon development.

Table of Contents

Introduction 1

Extension of current methods for allyl- transfer reactions

11

Novel synthon with two centers of reactivity for allyl transfer

12 Results and Discussion 15 Menthol based synthon and rearrangements 15 Studies of a synthon with two centers of reactivity 22

Conclusions and future directions

28 Experimental details 30 References 49

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