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Bulky phosphines and precursors to expand your toolbox

CYTOP® 242 (Strem Catalog: 97-1000) (di-tert-butylphosphine) is an alkyl phosphine that can be employed as a ligand building block for more complex ligands in catalysis (1). As a commercial and readily available molecule, it is an ideal candidate for the production of ligands that require large steric bulk. Unlike adamantyl phosphines, tertiary butyl systems are available from small (gram) to large (ton) volume rather readily making it an ideal candidate from a supply standpoint for all scales. It has been employed in catalysis for hydroamination and other catalytic reactions (2,3). CYTOP® 242T (Strem Catalog 97-1044) can also act as a ligand for ferrocene based ligands (4). Furthermore, it has been employed in “frustrated Lewis pair” (FLP) chemistry to synthesize catalytic phosphonium boranes (5, 6). Lastly, it has been studied as a support ligand in stereoselective synthesis of alkenes (7).

CYTOP® 242
Strem Catalog: 97-1000
CAS: 819-19-2

One application of CYTOP® 242 (Strem Catalog 97-1000) is as a precursor for chiral ferrocene ligands (Scheme 1) which are employed in the cyclization reaction of allenes. In this particular case a chiral transformation is also a requisite of the reaction. Also, a bulky secondary phosphine is required in order to effectively facilitate the reaction.

Scheme 1: Example of CYTOP® 242 being built into the ligand for a cyclization reaction

CYTOP® 202 (Strem Catalog 97-1128) (di-tert-butyl(n-butyl)phosphine CAS# 29949-72-2), is derived from CYTOP® 242 (Strem Catalog 97-1000). This ligand represents a bulky tertiary phosphine which can be used as an alternative to cataCXium® ligands.

If we consider reactions such as the synthesis of hydroquinones (industrially relevant in pharmaceutical industry) the CYTOP® 202 (Strem Catalog 97-1128) out performs the cataCXium®. A ligand for multiple substituents in this ring forming reaction.(8)

CYTOP® 242 (Strem Catalog 97-1000) is a clear, colorless, pyrophoric liquid.  A secondary phosphine, di-tert-butylphosphine must be handled under an inert atmosphere.  It can readily be functionalized into tertiary phosphines under the correct conditions. CYTOP® 202 (Strem Catalog 97-1128) di-tert-butyl(n-butyl)phosphine is a colorless pyrophoric liquid and must be handled under an inert atmosphere. To learn more about other ligands for catalysis, please refer to the Solvay website.

References:

1. Chem. Eur. J. 2019, 25, 10818-10822.
2. Angew. Chem. Int. Ed. 2019, 58, 9994-9997.
3. J. Am. Chem. Soc. 1994, 116, 4062-4069.
4. Chinese Patent CN 108929345, Dec. 4, 2018.
5. Dalton Trans. 2007, 31, 3407-3414.
6. J. Am. Chem. Soc. 2008, 130, 12632-12633.
7. J. Am. Chem. Soc. 2016, 138, 8588-8594.
8. ChemCatChem 2011, 3, 1273-1276.

Featured Products:

97-1000 Di-t-butylphosphine, 98+% [CYTOP® 242 ORGANOPHOSPHINE] (819-19-2)

97-1128 Di-t-butyl(n-butyl)phosphine, min. 97% [CYTOP® 202 ORGANOPHOSPHINE] (29949-72-2)

Related Products:

CYTOP Products

Phosphorus Ligands and Compounds Booklet

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