Methods for conversion of tyrosine to p-hydroxystyrene and p-hydroxycinnamic acid
OwnerSteven W. Shuey, Mukesh C. Shahinventors
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Abstract
Three different reaction steps were combined to provide methods for preparing p-hydroxystyrene and p-hydroxycinnamic acid monomers from tyrosine. The three steps include reductive alkylation of tyrosine, followed by oxidation to the N-oxide, and thermal Cope elimination. During Cope elimination, either p-hydroxycinnamic acid or p-hydroxystyrene was produced depending on the absence or presence of base, respectively. Additionally, p-acetoxystyrene may be prepared by reacting the prepared p-hydroxystyrene either directly or after isolation with an acetylating agent.
Claims17
A method for the synthesis of p-hydroxycinnamic acid comprising:
- a) reacting tyrosine over a metal hydrogenation catalyst with a reaction mixture comprising:
- i) at least two equivalents of an aldehyde;
- and
- ii) hydrogen or a hydrogen donor;
- to form an N,N-dialkyltyrosine product having the general structure of Formula I:
- wherein R1 and R2 are C1 to C10 linear or branched alkyls;
- b) optionally isolating the N,N-dialkyltyrosine product;
- c) reacting the N,N dialkyltyrosine product with an oxidizing agent to form N,N dialkyltyrosine N-oxide having the general structure of Formula II:
- wherein R1 and R2 are C1 to C10 linear or branched alkyls;
- d) optionally isolating the N,N dialkyltyrosine N-oxide product;
- e) heating the N,N dialkyltyrosine N-oxide product to form a mixture of dialkylhydroxylamine by-product and p-hydroxycinnamic acid;
- and
- f) removing dialkylhydroxylamine by-product of step (e) wherein the p-hydroxycinnamic acid product is stabilized.
A method for the synthesis of p-hydroxystyrene comprising:
- a) reacting tyrosine over a metal hydrogenation catalyst with a reaction mixture comprising:
- i) at least two equivalents of an aldehyde;
- and
- ii) hydrogen or a hydrogen donor;
- to form an N,N-dialkyltyrosine product having the general structure of Formula I:
- wherein R1 and R2 are C1 to C10 linear or branched alkyls;
- b) optionally isolating the N,N-dialkyltyrosine product;
- c) reacting the N,N dialkyltyrosine product with an oxidizing agent for form an N,N dialkyltyrosine N-oxide product having the structure of Formula II:
- wherein R1 and R2 are C1 to C10 linear or branched alkyls;
- d) optionally isolating the N,N dialkyltyrosine N-oxide product;
- and
- e) heating the N,N dialkyltyrosine N-oxide product in the presence of a base wherein thermal decomposition occurs to form p-hydroxytsyrene.
A method for the synthesis of p-acetoxystyrene comprising:
- a) reacting tyrosine over a metal hydrogenation catalyst with a reaction mixture comprising:
- i) at least two equivalents of an aldehyde;
- and
- ii) hydrogen or a hydrogen donor;
- to form an N,N-dialkyltyrosine product having the general structure of Formula I:
- wherein R1 and R2 are C1 to C10 linear or branched alkyls;
- b) optionally isolating the N,N-dialkyltyrosine product;
- c) reacting the N,N dialkyltyrosine product with an oxidizing agentto form an N,N dialkyltyrosine N-oxide product having the general structure of Formula II:
- wherein R1 and R2 are C1 to C10 linear or branched alkyls;
- d) optionally isolating the N,N dialkyltyrosine N-oxide product;
- e) heating the N,N dialkyltyrosine N-oxide product with in the presence of base wherein thermal decomposition occurs to produce p-hydroxystyrene;
- f) optionally isolating the p-hydroxystyrene of (e);
- and
- g) reacting the p-hydroxystyrene with an acetylating agent wherein p-acetoxystyrene is formed.
Dependencies are inferred from the claim text.