José M. Odriozola

Asymmetric synthesis of propargylic alcohols via aldol reaction of aldehydes with ynals promoted by prolinol ether–transition metal–Brønsted acid cooperative catalysis

A catalytic and highly stereoselective entry to propargylic alcohols and products derived thereof is reported based on an unprecedented cross-aldol coupling between unmodified aldehydes and ynals. The method requires an amine–metal salt–Bronsted acid ternary catalyst system and implies synergistic activation of the donor aldehyde via enamine and of the acceptor carbonyl via unique and reversible metal–alkyne complexation. Specifically, by using a combined a,a-dialkylprolinol silyl ether–CuI–PhCO2H catalyst system, remarkably high levels of diastereo- and enantioselectivity (anti/syn up to >20 : 1, ee up to >99%) are achieved.

A short formal synthesis of the carbapenem antibiotic (±)-PS-5

A practical stereoselective synthesis of 4-acetoxy-3-ethylazetidin-2-one via Reformatsky reaction between methyl-α-bromobutyrate and N-4-methoxyphenyl-α-methylcinnamyildeneamine is described.

Asymmetric synthesis of phoenicol, ferrugineol and cruentol, aggregation pheromones of Rhynchophorus spp.

Abstract Syntheses of phoenicol, ferrugineol, and cruentol, aggregation pheromones of Rhynchophorus palm weevils, have been achieved with an overall yield of 42, 40 and 41%, respectively (five steps), in high enantiomeric purity.

Diastereoselective [2 + 2] cycloaddition of dichloroketene with α-oxyaldehydes and α-amino aldehydes

A new route to natural products containing 1,2-diol and 1,2-amino alcohol subunits based on the [2 + 2] cycloaddition of dichloroketene to α-oxyaldehydes and α-amino aldehydes is demonstrated.

Asymmetric synthesis of (R)-4-hexanolide, the pheromone of Trogoderma glabrum

Synthesis of (R)-4-hexanolide, a sexual pheromone of Trogoderma glabrum, has been achieved with an overall yield of 45.4% in high enantiomeric purity using a chiral auxiliary derived from (S)-camphor.

Asymmetric Assembly of All-Carbon Tertiary/Quaternary Nonadjacent Stereocenters through Organocatalytic Conjugate Addition of α-Cyanoacetates to a Methacrylate Equivalent

An efficient, highly diastereo- and enantioselective assembly of acyclic carbonyl fragments possessing nonadjacent all-carbon tertiary/quaternary stereoarrays is reported based on a Brønsted base catalyzed Michael addition/α-protonation sequence involving α-cyanoacetates and 2,4-dimethyl-4-hydroxypenten-3-one as novel methacrylate equivalent.

The α-bromoester-imine condensation promoted by zinc-trimethylchlorosilane: a stereospecific short formal synthesis of (±)-carbapenem antibiotics and related compounds

Ethyl bromoacetate reacts with imines in the presence of zinc activated by trimethylchlorosilane to give high yields of 3-unsubstituted β-lactams.

The acid chloride–iminoester condensation: a direct approach to PS-5 and PS-6 intermediates and related compounds

The dehydrochlorination of alkanoyl chlorides with triethylamine in the presence of α-iminoesters produced 3-alkyl-4-alkoxycarbonyl β-lactams in excellent yields and high stereoselectivity.

Catalytic Enantioselective Quick Route to Aldol‐Tethered 1,6‐ and 1,7‐Enynes from ω‐Unsaturated Aldehydes

An effective asymmetric route to functionalized 1,6- and 1,7-enynes has been developed based on a direct cross-aldol reaction between ω-unsaturated aldehydes and propargylic aldehydes (α,β-ynals) promoted by combined α,α-dialkylprolinol ether/Brønsted acid catalysis. This synergistic activation strategy is key to accessing the corresponding aldol adducts with high stereoselectivity, both enantio- and diastereoselectivity. The aldol reaction also proceeds well with propargylic ketones (α,β-ynones) thus enabling a stereocontrolled access to the corresponding tertiary alcohols. The utility of these adducts, which are difficult to prepare through standard methodology, is demonstrated by their transformation into trisubstituted bicyclic enones using standard Pauson-Khand conditions.

α-Hydroxy Ketones as Masked Ester Donors in Brønsted Base Catalyzed Conjugate Additions to Nitroalkenes

The catalyst-controlled enantioselective direct addition reaction of enolizable esters and related carboxylic acid derivatives to π electrophiles remains a difficult synthetic transformation. In this study, the suitability of α-hydroxy ketones as ester equivalents capable of being activated by bifunctional Brønsted base catalysts in the context of conjugate addition reactions to nitroolefins is demonstrated. The scope of the reaction, which affords the corresponding Michael adducts with very high stereoselectivity (diastereomeric ratio (d.r.) ≥95:5, up to 99 % enantiomeric excess (ee)), and its limitations are explored, as is the aftermath elaboration of adducts into densely functionalized enantioenriched products.