Enantioselective Total Synthesis of (−)‐Blennolide A

Blennolide A can be synthesized through an enantioselective domino‐Wacker/carbonylation/methoxylation reaction of 7 a with 96 % ee and an enantioselective Wacker oxidation of 7 b with 89 % ee. Further transformations led to the α,β‐unsaturated ester (E)‐ 17 , which was subjected to a highly selective Michael addition, introducing a methyl group to give 18 a . After a threefold oxidation and an intramolecular acylation, the tetrahydroxanthenone 4 was obtained, which could be transformed into (?)‐blennolide A (ent‐ 1 ) in a few steps.     

A Domino Approach to the Enantioselective Total Syntheses of Blennolide C and Gonytolide C

The first enantioselective total syntheses of the tetrahydroxanthenone (?)‐blennolide C (ent‐ 4 ) and related γ‐lactonyl chromanone (?)‐gonytolide C (ent‐ 3 ) are reported. Key to the syntheses is an enantioselective domino‐Wacker/carbonylation/methoxylation reaction to set up the stereocentre at C‐4a. Various chiral BOXAX ligands were investigated, including novel (S,S)‐iBu‐BOXAX, and allowed access to chromane 8 in an excellent enantioselectivity of 99 %. The second stereocentre at C‐4 was established employing a diastereoselective Sharpless dihydroxylation. An extensive survey of (DHQ)‐ and (DHQD)‐based ligands enabled the preparation of both the anti‐isomer 14 a and the syn‐isomer 14 b in very good to reasonable selectivities of 13.7:1 and 1:3.7, respectively. While 14 a was further converted to ent‐ 3 and ent‐ 4 , 14 b was elaborated to syn‐acid 25 and 2′‐epi‐gonytolide C 28 .     

Redox Reaction of the Pd0 Complex Bearing the Trost Ligand with meso‐Cycloalkene‐1,4‐biscarbonates Leading to a Diamidato PdII Complex and 1,3‐Cycloalkadienes: Enantioselective Desymmetrization Versus Catalyst Deactivation

The Pd⁰ complex 1 that bears the Trost ligand 2 undergoes a facile redox reaction with 1,4‐biscarbonates 5 b – d and rac‐ 22 under formation of the diamidato–Pd^II complex 7 and the corresponding 1,3‐cycloalkadienes 8 b – d . The redox deactivation of complex 1 was the dominating pathway in the reaction of 5 b – d with HCO₃^? at room temperature. However, at 0 °C the six‐membered biscarbonate 5 b , catalytic amounts of complex 1 , and HCO₃^? mainly reacted in an allylic alkylation, which led to a highly selective desymmetrization of the substrate and gave alcohol 6 b with ≥99 % ee in 66 % yield. An increase of the catalyst loading in the reaction of 5 b with 1 and HCO₃^? afforded the bicyclic carbonate 12 b (96 % ee, 92 %). Formation of carbonate 12 b involves two consecutive inter‐ and intramolecular substitution reactions of the π‐allyl–Pd^II complexes 16 b and 18 b , respectively, with O‐nucleophiles and presumably proceeds through the hydrogen carbonate 17 b as key intermediate. The intermediate formation of 17 b is also indicated by the conversion of alcohol rac‐ 6 b to carbonate 12 b upon treatment with HCO₃^? and 1 . The Pd⁰‐catalyzed desymmetrization of 5 b with formation of 12 b and its hydrolysis allow an efficient enantioselective synthesis of diol 13 b . The reaction of the seven‐membered biscarbonate 5 c with ent‐ 1 and HCO₃^? afforded carbonate ent‐ 12 c (99 % ee, 39 %). The Pd⁰ complex 1 is stable in solution and suffers no intramolecular redox reaction with formation of complex 7 and dihydrogen as recently claimed for the similar Pd⁰ complex 9 . Instead, complex 1 is rapidly oxidized by dioxygen to give the stable Pd^II complex 7 . Thus, formation of the Pd^II complex 10 from 9 was most likely due to an oxidation by dioxygen. Oxidative workup (air) of the reaction mixture stemming from the desymmetrization of 5 c catalyzed by 1 gave the Pd^II complex 7 in high yield besides carbonate 12 c .     

Total Synthesis of (−)‐Zampanolide and Structure–Activity Relationship Studies on (−)‐Dactylolide Derivatives

A new total synthesis of the marine macrolide (?)‐zampanolide ( 1 ) and the structurally and stereochemically related non‐natural levorotatory enantiomer of (+)‐dactylolide ( 2 ), that is, ent‐ 2 , has been developed. The synthesis features a high‐yielding, selective intramolecular Horner–Wadsworth–Emmons (HWE) reaction to close the 20‐membered macrolactone ring of 1 and ent‐ 2 . The β‐keto phosphonate/aldehyde precursor for the ring‐closure reaction was obtained by esterification of a ω‐diethylphosphono carboxylic acid fragment and a secondary alcohol fragment incorporating the THP ring that is embedded in the macrocyclic core structure of 1 and ent‐ 2 . THP ring formation was accomplished through a segment coupling Prins‐type cyclization. Employing the same overall strategy, 13‐desmethylene‐ent‐ 2 as well as the monocyclic desTHP derivatives of 1 and ent‐ 2 were prepared. Synthetic 1 inhibited human cancer cell growth in vitro with nM IC₅₀ values, while ent‐ 2 , which lacks the diene‐containing hemiaminal‐linked side chain of 1 , is 25‐ to 260‐fold less active. 13‐Desmethylene‐ent‐ 2 as well as the reduced versions of ent‐ 2 and 13‐desmethylene‐ent‐ 2 all showed similar cellular activity as ent‐ 2 itself. The same activity level was attained by the monocyclic desTHP derivative of 1 . Oxidation of the aldehyde functionality of ent‐ 2 gave a carboxylic acid that was converted into the corresponding N‐hexyl amide. The latter showed only μM antiproliferative activity, thus being several hundred‐fold less potent than 1 .     

Direct Synthesis of Chiral 3‐Arylsuccinimides by Rhodium‐Catalyzed Enantioselective Conjugate Addition of Arylboronic Acids to Maleimides

Chiral rhodium catalysts comprising 2,5‐diaryl‐ substituted bicyclo[2.2.1]diene ligands L1 – L10 were utilized in the enantioselective 1,4‐addition reaction of arylboronic acids to N‐substituted maleimides. In the presence of 2.5 mol % of Rh^I/ L2 , enantioenriched conjugate addition adducts were isolated in 72–99 % yields with 86–98 % ee. This protocol offers a convenient method to access a variety of 3‐arylsuccinimides in a highly enantioselective manner. Maleimides with readily cleavable N‐protecting groups were tolerated enabling the synthesis of useful synthetic intermediates. Pyrrolidine 4 , a biologically active compound, and pyrrolidine 5 , an ent‐precursor to an HSD‐1 inhibitor, were synthesized to demonstrate the utility of this method.     

Enantioselective Total Synthesis of (+)‐Jungermatrobrunin A

A concise and enantioselective total synthesis of (+)‐jungermatrobrunin A ( 1 ), which features a unique bicyclo[3.2.1]octene ring skeleton with an unprecedented peroxide bridge, was accomplished in 13 steps by making use of a late‐stage visible‐light‐mediated Schenck ene reaction of (?)‐1α,6α‐diacetoxyjungermannenone C ( 2 ). Along the way, a UV‐light‐induced bicyclo[3.2.1]octene ring rearrangement afforded (+)‐12‐hydroxy‐1α,6α‐diacetoxy‐ent‐kaura‐9(11),16‐dien‐15‐one ( 4 ). These divergent photo‐induced skeletal rearrangements support a possible biogenetic relationship between (+)‐ 1 , (?)‐ 2 , and (+)‐ 4 .     

Enantioselectivity in Odor Perception

The 3‐methyl‐4‐(tricyclo[5.2.1.0^2,6]dec‐4‐en‐8‐ylidene)butan‐2‐ols (=Fleursandol^®; rac‐ 10 ), a new class of sandalwood odorants, were synthesized in their enantiomerically pure forms by use of tricyclo[5.2.1.0^2,6]dec‐4‐en‐8‐ones 17 and ent‐ 17 and (tetrahydro‐2H‐pyran‐2‐yl)‐protected 4‐bromo‐3‐methylbutan‐2‐ols 22 and ent‐ 22 as starting materials (Schemes 2–4). Only four of 16 possible stereoisomers of rac‐ 10 possess the typical, very pleasant, long‐lasting sandalwood odor (Table 1). The (2S,3R,4E,1′R,2′R,6′R,7′R)‐isomer ent‐ 10a is by far the most important representative, with an odor threshold of 5 μg/l in H₂O.     

Diastereo‐ and Enantioselective Intramolecular [2+2] Photocycloaddition Reactions of 3‐(ω′‐Alkenyl)‐ and 3‐(ω′‐Alkenyloxy)‐Substituted 5,6‐Dihydro‐1H‐pyridin‐2‐ones

3‐(ω′‐Alkenyl)‐substituted 5,6‐dihydro‐1H‐pyridin‐2‐ones 2 – 4 were prepared as photocycloaddition precursors either by cross‐coupling from 3‐iodo‐5,6‐dihydro‐1H‐pyridin‐2‐one ( 8 ) or—more favorably—from the corresponding α‐(ω′‐alkenyl)‐substituted δ‐valerolactams 9 – 11 by a selenylation/elimination sequence (56–62 % overall yield). 3‐(ω′‐Alkenyloxy)‐substituted 5,6‐dihydro‐1H‐pyridin‐2‐ones 5 and 6 were accessible in 43 and 37 % overall yield from 3‐diazopiperidin‐2‐one ( 15 ) by an α,α‐chloroselenylation reaction at the 3‐position followed by nucleophilic displacement of a chloride ion with an ω‐alkenolate and oxidative elimination of selenoxide. Upon irradiation at λ=254 nm, the precursor compounds underwent a clean intramolecular [2+2] photocycloaddition reaction. Substrates 2 and 5 , tethered by a two‐atom chain, exclusively delivered the respective crossed products 19 and 20 , and substrates 3 , 5 , and 6 , tethered by longer chains, gave the straight products 21 – 23 . The completely regio‐ and diastereoselective photocycloaddition reactions proceeded in 63–83 % yield. Irradiation in the presence of the chiral templates (?)‐ 1 and (+)‐ 31 at ?75 °C in toluene rendered the reactions enantioselective with selectivities varying between 40 and 85 % ee. Truncated template rac‐ 31 was prepared as a noranalogue of the well‐established template 1 in eight steps and 56 % yield from the Kemp triacid ( 24 ). Subsequent resolution delivered the enantiomerically pure templates (?)‐ 31 and (+)‐ 31 . The outcome of the reactions is compared to the results achieved with 4‐substituted 5,6‐dihydro‐1H‐pyridin‐2‐ones and quinolones.     

Concise Approach to (ent)‐14 β‐Hydroxysteroids through Highly Diastereo‐/Enantioselective Diels–Alder Reactions

14β‐Hydroxysteroids, especially 14β‐hydroxyandrostane derivatives are closely related to the cardenolide skeletons. The latter were readily available through highly diastero/enantioselective Diels–Alder (DA) reactions requiring high pressure or Lewis acid activation. Moreover, in the presence of (R)‐ or (S)‐carvone as a chiral dienophile, the DA‐reaction takes place under chemodivergent parallel kinetic resolution control affording highly enantiomerically enriched 14β‐hydroxysteroid derivatives or the corresponding (ent)‐14β‐hydroxysteroid derivatives.     

Total Syntheses of Tubulysins

The total syntheses of tetrapeptides tubulysins D ( 1 b ), U ( 1 c ), and V ( 1 d ), which are potent tubulin polymerization inhibitors, are described. The synthesis of Tuv ( 2 ), an unusual amino acid constituent of tubulysins, includes an 1,3‐dipolar cycloaddition reaction of chiral nitrone D ‐ 6 derived from D ‐gulose with N‐acryloyl camphor sultam (?)‐ 9 employing the double asymmetric induction, whereas the synthesis of Tup ( 20 ), another unusual amino acid, involves a stereoselective Evans aldol reaction of (Z)‐boron enolate generated from (S)‐4‐isopropyl‐3‐propionyl‐2‐oxazolidinone with N‐protected phenylalaninal and a subsequent Barton deoxygenation protocol. We accomplished the total syntheses of tubulysins U ( 1 c ) and V ( 1 d ) by using these methodologies, in which the isoxazolidine ring was used as the effective protective group for γ‐amido alcohol functionality. Furthermore, to understand the structure‐activity relationship of tubulysins, we synthesized tubulysin D ( 1 b ) and cyclo‐tubulysin D ( 1 e ) from 2 ‐Me and 20 , and ent‐tubulysin D (ent‐ 1 d ) from ent‐ 2 ‐Me and ent‐ 20 , respectively. The preliminary results regarding their biological activities are also reported.     

Platinum(II) Complexes of P‐Chiral 1, 8‐Bis(diorganophosphino)naphthalenes; Crystal Structures of dmfppn,rac‐[PtCl2(dmfppn)], and rac‐[PtCl2(dtbppn)] (dmfppn = 1, 8‐di(methyl‐pentafluorophenylphosphino)naphthalene and dtbppn = 1, 8‐di(tert‐butylphenylphosphino)naphthalene)

The reaction of 1, 8‐dilithionaphthalene 2 , with 2 equivalents of rac‐Me(C₆F₅)PCl, gave a 6 : 1 mixture of rac‐ and meso‐1, 8‐di(methyl‐pentafluorophenylphosphino)naphthalene (dmfppn, rac‐ 3h and meso‐ 3h ), but no reaction was observed when the sterically crowded rac‐tBu(C₆F₅)PCl was used. In ³¹P NMR experiments, rac‐ 3h and mmeso‐ 3h exhibited characteristic signals (virtual quintets), which indicate that there is significant coupling through space (³J_PF + ⁷ J_PF ≈ 15 Hz). Compound rac‐ 3h was isolated by fractional crystallisation and treated with aqueous H₂O₂ to yield the corresponding bis‐phosphine dioxide, rac‐ 7h . In contrast to rac‐ 3h , there was no sign of through‐space coupling in rac‐ 7h , which again illustrates that the latter operates via the lone pairs at phosphorus. Platinum(II) complexes were prepared from the new, P‐chiral chelate rac‐ 3h , and the related ligand 1, 8‐di(tert‐butylphenylphosphino) naphthalene (rac‐dtbppn, rac‐ 3e ). All isolated new compounds were characterised by multinuclear NMR and IR spectroscopy, mass spectrometry, and elemental analysis. Single‐crystal X‐ray structure determinations were performed for rac‐dmfppn (rac‐ 3h ), rac‐[PtCl₂(dtbppn)] (rac‐ 17e ), and rac‐[PtCl₂(dmfppn)] (rac‐ 17h ). rac‐ 3h displays crystallographic twofold symmetry. In rac‐ 17h , the electron‐withdrawing effect of the C₆F₅ groups causes a shortening of the P_t—P bond to ca. 220 pm (cf. 223 pm in rac‐ 17e ).     

Analogues of α‐Campholenal (= (1R)‐2,2,3‐Trimethylcyclopent‐3‐ene‐1‐acetaldehyde) as Building Blocks for (+)‐β‐Necrodol (= (1S,3S)‐2,2,3‐Trimethyl‐4‐methylenecyclopentanemethanol) and Sandalwood‐like Alcohols

To complete our panorama in structure–activity relationships (SARs) of sandalwood‐like alcohols derived from analogues of α‐campholenal (= (1R)‐2,2,3‐trimethylcyclopent‐3‐ene‐1‐acetaldehyde), we isomerized the epoxy‐isopropyl‐apopinene (?)‐ 2d to the corresponding unreported α‐campholenal analogue (+)‐ 4d (Scheme 1). Derived from the known 3‐demethyl‐α‐campholenal (+)‐ 4a , we prepared the saturated analogue (+)‐ 5a by hydrogenation, while the heterocyclic aldehyde (+)‐ 5b was obtained via a Bayer‐Villiger reaction from the known methyl ketone (+)‐ 6 . Oxidative hydroboration of the known α‐campholenal acetal (?)‐ 8b allowed, after subsequent oxidation of alcohol (+)‐ 9b to ketone (+)‐ 10 , and appropriate alkyl Grignard reaction, access to the 3,4‐disubstituted analogues (+)‐ 4f,g following dehydration and deprotection. (Scheme 2). Epoxidation of either (+)‐ 4b or its methyl ketone (+)‐ 4h , afforded stereoselectively the trans‐epoxy derivatives 11a,b , while the minor cis‐stereoisomer (+)‐ 12a was isolated by chromatography (trans/cis of the epoxy moiety relative to the C₂ or C₃ side chain). Alternatively, the corresponding trans‐epoxy alcohol or acetate 13a,b was obtained either by reduction/esterification from trans‐epoxy aldehyde (+)‐ 11a or by stereoselective epoxidation of the α‐campholenol (+)‐ 15a or of its acetate (?)‐ 15b , respectively. Their cis‐analogues were prepared starting from (+)‐ 12a . Either (+)‐ 4h or (?)‐ 11b , was submitted to a Bayer‐Villiger oxidation to afford acetate (?)‐ 16a . Since isomerizations of (?)‐ 16 lead preferentially to β‐campholene isomers, we followed a known procedure for the isomerization of (?)‐epoxyverbenone (?)‐ 2e to the norcampholenal analogue (+)‐ 19a . Reduction and subsequent protection afforded the silyl ether (?)‐ 19c , which was stereoselectively hydroborated under oxidative condition to afford the secondary alcohol (+)‐ 20c . Further oxidation and epimerization furnished the trans‐ketone (?)‐ 17a , a known intermediate of either (+)‐β‐necrodol (= (+)‐(1S,3S)‐2,2,3‐trimethyl‐4‐methylenecyclopentanemethanol; 17c ) or (+)‐(Z)‐lancifolol (= (1S,3R,4Z)‐2,2,3‐trimethyl‐4‐(4‐methylpent‐3‐enylidene)cyclopentanemethanol). Finally, hydrogenation of (+)‐ 4b gave the saturated cis‐aldehyde (+)‐ 21 , readily reduced to its corresponding alcohol (+)‐ 22a . Similarly, hydrogenation of β‐campholenol (= 2,3,3‐trimethylcyclopent‐1‐ene‐1‐ethanol) gave access via the cis‐alcohol rac‐ 23a , to the cis‐aldehyde rac‐ 24 .     

gem‐Dihalocyclopropanes as Building Blocks in Natural‐Product Synthesis: Enantioselective Total Syntheses of ent‐Erythramine and 3‐epi‐Erythramine

ent‐Erythramine ((?)‐ 1 ), the enantiomer of the alkaloid erythramine, was prepared in 15 steps from known compounds. The first of three pivotal bond‐forming steps in the synthesis was a Suzuki–Miyaura cross‐coupling reaction of the starting materials to give a bis‐silyl ether. The second involved silver(I)‐induced electrocyclic ring opening of the gem‐dichlorocyclopropane formed in the next step and trapping of the ensuing π‐allyl cation by the tethered nitrogen atom to give, following cleavage of the allyloxycarbonyl protecting group, an approximately 5:6 mixture of the chromatographically separable diastereoisomeric spirocyclic products. In the third critical bond‐forming reaction, the iodide formed from one of the diastereoisomers underwent a radical‐addition/elimination reaction sequence that led to (?)‐ 1 in 89 % yield. The application of the same sequence of transformations to the other diastereoisomer afforded 3‐epi‐(+)‐erythramine (3‐epi‐(+)‐ 1 ).     

Pd(II)‐Catalyzed Tandem Enantioselective Methylene C(sp3)−H Alkenylation–Aza‐Wacker Cyclization to Access β‐Stereogenic γ‐Lactams

Herein, we describe an unprecedented cascade reaction to β‐stereogenic γ‐lactams involving Pd(II)‐catalyzed enantioselective aliphatic methylene C(sp³)?H alkenylation–aza‐Wacker cyclization through syn‐aminopalladation. Readily available 3,3′‐substituted BINOLs are used as chiral ligands, providing the corresponding γ‐lactams with broad scope and high enantioselectivities (up to 98 % ee).     

Total Synthesis of the 7,10‐Epimer of the Proposed Structure of Amphidinolide N,Part I: Synthesis of the C1–C13 Subunit

Amphidinolide N, the structure of which has been recently revised, is a 26‐membered macrolide featuring allyl epoxide and tetrahydropyran moieties with 13 chiral centers. Due to its challenging structure and extraordinary potent cytotoxicity, amphidinolide N is a highly attractive target of total synthesis. During our total synthesis studies of the 7,10‐epimer of the proposed structure of amphidinolide N, we have synthesized the C1–C13 subunit enantio‐ and diastereoselectively. Key reactions include an l ‐proline catalyzed enantioselective intramolecular aldol reaction, Evans aldol reaction, Sharpless asymmetric epoxidation and Tamao–Fleming oxidation. To aid late‐stage manipulations, we also developed the 4‐(N‐benzyloxycarbonyl‐N‐methylamino)butyryl group as a novel ester protective group for the C9 alcohol.     

Room‐temperature Suzuki–Miyaura cross‐coupling reaction with α‐diimine Pd(II) catalysts

An α‐diimine Pd(II) complex containing chiral sec‐phenethyl groups, {bis[N,N′‐(4‐methyl‐2‐sec‐phenethylphenyl)imino]‐2,3‐butadiene}dichloropalladium (rac‐ C1 ), was synthesized and characterized. rac‐ C1 was applied as an efficient catalyst for the Suzuki–Miyaura cross‐coupling reaction between various aniline halides and arylboronic acid in PEG‐400–H₂O at room temperature. Among a series of aniline halides, rac‐ C1 did not catalyze the cross‐coupling of aniline chlorides and fluorides but efficiently catalyzed the cross‐coupling of aniline bromides and iodides with phenylboronic acid. The catalytic activity reduced slightly with increasing steric hindrance of the aniline bromides. The complexes {bis[N,N′‐(4‐fluoro‐2,6‐diphenylphenyl)imino]‐2,3‐butadiene}dichloropalladium and {bis[N,N′‐(4‐fluoro‐2,6‐diphenylphenyl)imino]acenaphthene}dichloropalladium were also found to be efficient catalysts for the reaction. Copyright © 2015 John Wiley & Sons, Ltd.     

Palladium‐Catalyzed Enantioselective Desymmetrizing Aza‐Wacker Reaction: Development and Application to the Total Synthesis of (−)‐Mesembrane and (+)‐Crinane

Reported is an unprecedented catalytic enantioselective desymmetrizing aza‐Wacker reaction. In the presence of a catalytic amount of a newly developed Pd(CPA)₂(MeCN)₂ catalyst (CPA=chiral phosphoric acid), a pyrox ligand, and molecular oxygen, cyclization of properly functionalized prochiral 3,3‐disubstituted cyclohexa‐1,4‐dienes afforded enantioenriched cis‐3a‐substituted tetrahydroindoles in good yields with excellent enantioselectivities. A cooperative effect between the phosphoric acid and the pyrox ligand ensured efficient transformation. This reaction was tailor‐made for Amaryllidaceae and Sceletium alkaloids as illustrated by its application in the development of the concise and divergent total synthesis of (?)‐mesembrane and (+)‐crinane.     

Enantioselective Total Synthesis of Secalonic Acid E

The first enantioselective synthesis of a secalonic acid containing a dimeric tetrahydroxanthenone skeleton is described, using a Wacker‐type cyclization of a methoxyphenolic compound to form a chiral chroman with a quaternary carbon stereogenic center with >99 % ee. Further steps are a Sharpless dihydroxylation and a Dieckmann condensation to give a tetrahydroxanthenone. A late‐stage one‐pot palladium‐catalyzed Suzuki‐dimerization reaction leads to the 2,2′‐biphenol linkage to complete the enantioselective total synthesis of secalonic acid E in 18 steps with 8 % overall yield.     

(+)‐(R,Z)‐5‐Muscenone and (−)‐(R)‐Muscone by Enantioselective Aldol Reaction and Grob Fragmentation

(+)‐(R,Z)‐5‐Muscenone ((R)‐ 1 ) was synthesized by an enantioselective aldol reaction, catalyzed by new ephedrine‐type Ti reagents (up to 70 % enantiomeric excess). Substrate‐directed diastereoselective reduction of the aldol product and Grob fragmentation of the tosylate of the resultant 1,3‐diol afforded (+)‐ 1 . This approach also gave access to (?)‐(R,E)‐5‐muscenone and (?)‐(R)‐muscone.     

Enantioselective Syntheses of Lignin Models: An Efficient Synthesis of β‐O‐4 Dimers and Trimers by Using the Evans Chiral Auxiliary

We describe an efficient five‐step, enantioselective synthesis of (R,R)‐ and (S,S)‐lignin dimer models possessing a β‐O‐4 linkage, by using the Evans chiral aldol reaction as a key step. Mitsunobu inversion of the (R,R)‐ or (S,S)‐isomers generates the corresponding (R,S)‐ and (S,R)‐diastereomers. We further extend this approach to the enantioselective synthesis of a lignin trimer model. These lignin models are synthesized with excellent ee (>99 %) and high overall yields. The lignin dimer models can be scaled up to provide multigram quantities that are not attainable by using previous methodologies. These lignin models will be useful in degradation studies probing the selectivity of enzymatic, microbial, and chemical processes that deconstruct lignin.