Chemo-enzymatic total synthesis: current approaches toward the integration of chemical and enzymatic transformations

• Ryo Tanifuji and
• Hiroki Oguri

Beilstein J. Org. Chem. 2024, 20, 1693–1712, doi:10.3762/bjoc.20.151

• -half segment 72 was prepared from mixed anhydride 68 (Scheme 8A). Condensation with chiral auxiliary 69 and subsequent diastereoselective alkylation, followed by reductive removal of the auxiliary and iodination of the resulting primary alcohol provided alkyl iodide 70 [78]. Subsequent six-step

• transformations including diastereoselective alkylation of (+)-pseudoephedrine derivative 71 [79] with the iodide 70, sequential functional group manipulations, and installation of the β-ketophosphonate, provided the left-half segment 72 [80]. The right-half segment 75 was synthesized in six steps via

The chemistry and biology of mycolactones

• Matthias Gehringer and
• Karl-Heinz Altmann

Beilstein J. Org. Chem. 2017, 13, 1596–1660, doi:10.3762/bjoc.13.159

• iodide 21. As illustrated in Scheme 2, the nine-step synthesis of the latter proceeded via key epoxide 30 and comprised a diastereoselective alkylation of diethyl (S)-malate according to Seebach and Wasmuth [136] to introduce the C12-methyl group (dr = 8:1). Although being longer than the 1st generation

Synthesis of enantiomerically enriched (R)-¹³C-labelled 2-aminoisobutyric acid (Aib) by conformational memory in the alkylation of a derivative of L-alanine

• Stephen P. Fletcher,
• Jordi Solà,
• Dean Holt,
• Robert A. Brown and
• Jonathan Clayden

Beilstein J. Org. Chem. 2011, 7, 1304–1309, doi:10.3762/bjoc.7.152

• quaternary amino acids [15][16][17][18][19][20] fall principally into three classes. In the first, exemplified by the method of Schöllkopf [21][22][23][24], a diastereoselective alkylation is used to relay the stereochemistry of an existing stereogenic centre to the new quaternary centre. In the second

• , (R)-6* was obtained in 93% yield on a 400 mg scale, as a 2.1:1 ratio of enantiomers. The products of related alkylations are reported [36] to arise from the diastereoselective alkylation of the conformationally locked enolate 4 whose stereochemistry results from the selective deprotonation of the

Asymmetric synthesis of tertiary thiols and thioethers

• Jonathan Clayden and
• Paul MacLellan

Beilstein J. Org. Chem. 2011, 7, 582–595, doi:10.3762/bjoc.7.68

• alkene towards attack by the sulfur nucleophile. 2 Carbon–carbon bond formation 2.1 Electrophilic addition to α-thioenolates Diastereoselective alkylation of α-thioenolates has been used to prepare several types of enantiomerically pure tertiary thioethers [49][50][51][52][53][54]. The method of “self

Application of the diastereoselective photodeconjugation of α,β-unsaturated esters to the synthesis of gymnastatin H

• Ludovic Raffier and
• Olivier Piva

Beilstein J. Org. Chem. 2011, 7, 151–155, doi:10.3762/bjoc.7.21

• dienoate chain. The configuration at the C-2 carbon atom of this precursor was controlled by using a diastereoselective alkylation of an acyl oxazolidinone. In some cases, a Claisen condensation took place and afforded a β-ketoamide in noticeable amounts diminishing the overall yield of the sequence [15

2-Phenyl- tetrahydropyrimidine- 4(1H)-ones – cyclic benzaldehyde aminals as precursors for functionalised β²-amino acids

• Markus Nahrwold,
• Arvydas Stončius,
• Anna Penner,
• Beate Neumann,
• Hans-Georg Stammler and
• Norbert Sewald

Beilstein J. Org. Chem. 2009, 5, No. 43, doi:10.3762/bjoc.5.43

• serve as universal precursors for the asymmetric synthesis of functionalised β2-amino acids containing acid-labile protected side chains. Diastereoselective alkylation of the tetrahydropyrimidinone is followed by a chemoselective two step degradation of the heterocycle to release the free β2-amino acid

• . In the course of this study, an L-asparagine derivative was condensed with benzaldehyde and subsequently converted to orthogonally protected (R)-β2-homoaspartate. Keywords: β2-amino acids; cyclocondensation; diastereoselective alkylation; N,N-acetals; peptidomimetics; ring opening; self-regeneration

• were both used a starting materials for diastereoselective alkylation experiments. Attempts to enolise 5 at −78 °C by reaction with NaHMDS or LiHMDS, followed by addition of benzyl bromide did not lead to any alkylation product. Instead, the starting material was re-isolated. Addition of sodium iodide