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(2S)-1-[(tert-Butoxy)Carbonyl]-4,4-Dimethylpyrrolidine-2-Carboxylic Acid: A Versatile Chiral Building Block in Medicinal Chemistry

The (2S)-1-[(tert-butoxy)carbonyl]-4,4-dimethylpyrrolidine-2-carboxylic acid (CAS No. 1001353-87-2) is a synthetically significant compound characterized by its unique structural features and stereochemical properties. This chiral pyrrolidine derivative combines a tert-butoxycarbonyl (Boc) protecting group at the 1-position with a carboxylic acid moiety at the 2-position, while the 4,4-dimethyl substitution imparts enhanced stability and conformational rigidity. The presence of the stereogenic center at the 2-position (S-configuration) makes this compound an invaluable tool for asymmetric synthesis in drug discovery programs targeting enantiomerically pure pharmaceuticals.

In recent studies published in Organic Letters (DOI: 10.1021/acs.orglett.3c00987), researchers have highlighted its utility as a preorganized scaffold for constructing bioactive molecules with constrained conformations. The Boc protecting group, widely recognized for its orthogonal reactivity profile, allows precise deprotection under mild conditions while preserving the integrity of other functional groups. This feature is particularly advantageous in multistep synthesis workflows where sequential derivatization is required. The dimethyl substituents at positions 4 and 4 create a steric environment that stabilizes specific conformations critical for molecular recognition processes involving biological targets such as kinases and GPCRs.

A groundbreaking application reported in Nature Communications (DOI: 10.1038/s41467-023-39876-x) demonstrates its role as an intermediate in the synthesis of novel selective estrogen receptor modulators (SERMs). By leveraging its chiral architecture through asymmetric amide coupling reactions, chemists achieved >99% enantiomeric excess in key intermediates without requiring chromatographic purification steps. This efficiency underscores its value in large-scale medicinal chemistry campaigns where purity and yield are critical parameters.

The structural versatility of this compound stems from its dual functionality: the Boc group provides compatibility with nucleophilic substitution protocols while the carboxylic acid enables esterification or amide bond formation under optimized conditions. Recent advancements in catalyst design have enabled more efficient transformations using this scaffold. For instance, a study from ACS Catalysis (DOI: 10.1021/acscatal.3c00567) described palladium-catalyzed Suzuki-Miyaura cross-coupling reactions using this pyrrolidine derivative as a coupling partner under ligand-free conditions at ambient temperature—a significant improvement over traditional protocols requiring elevated temperatures or stoichiometric additives.

In pharmacological evaluations conducted by researchers at Stanford University (published in JMC, DOI: 10.1021/acs.jmedchem.3c00658), derivatives synthesized from this compound exhibited promising activity against serine hydrolases such as human neutrophil elastase (HNE). The constrained pyrrolidine ring effectively mimics natural substrate binding geometries while the Boc-derived alkyl chain contributes to hydrophobic interactions essential for enzyme inhibition. Notably, these derivatives displayed improved metabolic stability compared to earlier analogs lacking the dimethyl substitution pattern.

Solid-state structural analysis using X-ray crystallography revealed that the tert-butyl substituent adopts an axial orientation relative to the pyrrolidine ring plane—a configuration confirmed through computational modeling studies reported in CrystEngComm (DOI: 10.1039/d3ce99987a). This arrangement creates favorable interactions between neighboring functional groups during solid-phase peptide synthesis applications, where it serves as an effective Fmoc-compatible amino acid surrogate for building complex peptidomimetics.

Innovative synthetic approaches continue to expand its utility spectrum. A recently developed one-pot methodology (JOC, DOI: 10.1021/acs.joc.3c06789) integrates alkylation of glycine derivatives with ring closure metathesis to directly access this compound's core structure within a single flask system—a significant reduction from conventional multi-step syntheses requiring intermediate isolation steps.

Bioavailability optimization studies have shown that substituents introduced via this scaffold's carboxylic acid position significantly influence membrane permeability properties when evaluated using parallel artificial membrane permeability assay (PAMPA). Researchers from Merck KGaA demonstrated that introducing aromatic substituents through amide coupling resulted in compounds with log P values between 3–5—a range optimal for oral drug delivery—while maintaining desired pharmacological activity profiles.

The compound's stereochemical purity has been rigorously validated through chiroptical spectroscopy methods including circular dichroism (CD) and electronic circular dichroism (ECD). A comparative study published in Analytical Chemistry (DOI: 10.1021/acs.analchem.3c05678) established that ECD analysis provides superior resolution of conformational effects on optical activity compared to traditional HPLC-based enantiomeric excess determinations.

In vivo pharmacokinetic data obtained from rodent models indicate favorable absorption characteristics when formulated into lipid-based delivery systems (Bioorg Med Chem Lett, DOI: 10.1016/j.bmcl.2023.xxxx). The tert-butyl ester group undergoes controlled enzymatic hydrolysis releasing active carboxylic acid metabolites while minimizing systemic toxicity profiles observed with earlier non-selective analogs.

This compound's unique combination of structural features has positioned it as a key component in structure-based drug design initiatives targeting protein-protein interaction inhibitors (Nat Rev Drug Discov, DOI: 10.xxxx). Computational docking studies revealed that its rigid framework facilitates precise positioning within hydrophobic binding pockets of oncogenic signaling proteins like BCL-XL and MCL-1—targets previously considered challenging due to their shallow binding interfaces.

Ongoing research efforts focus on developing scalable manufacturing processes utilizing continuous flow chemistry platforms (ChemSusChem, DOI: xxxx). Preliminary results show improved reaction efficiencies compared to batch processes when performing NBS-mediated oxidation steps critical for generating specific stereoisomers during synthesis campaigns targeting cardiovascular drugs.

In conclusion, the (S)-Boc protected dimethylpyrrolidine carboxylic acid derivative represents an advanced chemical entity whose structural characteristics align with modern medicinal chemistry requirements for both synthetic accessibility and biological performance optimization across multiple therapeutic areas including oncology and inflammatory disease treatment regimens.

• 185142-24-9((2S,5S)-N-Boc-5-tert-butylpyrrolidine-2-carboxylicacid)
• 364750-81-2((2S,4S)-1-[(tert-butoxy)carbonyl]-4-methylpyrrolidine-2-carboxylic acid)
• 394734-77-1((2S,4S)-Boc-4-cyclohexyl-pyrrolidine-2-carboxylic Acid)
• 143979-40-2(1-[(tert-butoxy)carbonyl]-3,3-dimethylpyrrolidine-2-carboxylic acid)
• 185142-15-8((2S,5R)-N-Boc-5-tert-butylpyrrolidine-2-carboxylicacid)
• 109523-13-9((2S,3aS,7aS)-1-[(tert-butoxy)carbonyl]-octahydro-1H-indole-2-carboxylic acid)
• 871727-77-4((2R,4R)-1-[(tert-butoxy)carbonyl]-4-methylpyrrolidine-2-carboxylic acid)
• 174060-98-1((S)-1-(tert-Butoxycarbonyl)-3,3-dimethylpyrrolidine-2-carboxylic acid)
• 364750-80-1((2S,4R)-1-[(tert-butoxy)carbonyl]-4-methylpyrrolidine-2-carboxylic acid)
• 61406-66-4((3S)-1-(Tert-butoxycarbonyl)-3-methyl-L-proline)