t-Butyl N-Lithio-N-(p-toluenesulfonyloxy)carbamate

[134953-60-9]  · C12H16LiNO5S  · t-Butyl N-Lithio-N-(p-toluenesulfonyloxy)carbamate  · (MW 293.26)

(electrophilic aminating agent for several carbanions;1 can react with organoboranes to produce N-Boc protected primary amines2)

Solubility: sol THF and diethyl ether.

Preparative Method: prepared from t-butyl N-(p-toluenesulfonyloxy)carbamate and n-Butyllithium at -78 °C in anhydrous THF.

Handling, Storage, and Precautions: should be used immediately as prepared for best results.

Electrophilic Amination.

t-Butyl N-lithio-N-(p-toluenesulfonyloxy)carbamate (1) is prepared from t-butyl N-(p-toluenesulfonyloxy)carbamate, which is easily obtained on a large scale by tosylation of the commercially available t-butyl N-hydroxycarbamate.3 (1) is an electrophilic aminating reagent and a synthetic equivalent of +NHBoc. It reacts with alkyllithium reagents (eq 1)1a or arylcopper reagents (eq 2)1b to provide primary amines in their N-Boc protected form.

Zinc ester enolates react with (1) to give the corresponding N-Boc a-amino carboxylic esters in moderate yield (eq 3).1a In contrast, diethyl a-cuprophosphonates give N-Boc a-amino phosphonic esters in acceptable yields (eq 4).1a

Reaction with Organoboranes.2

Primary and secondary alkylboranes react rapidly at low temperature with (1) to give the corresponding N-Boc protected primary amines (eq 5). The reaction presumably proceeds via the anionotropic rearrangement of an organoborate complex (eq 6). N-Boc protected aniline is obtained from triphenylborane under the same conditions with a yield of 16%. This yield can be increased by using the potassium form of the aminating reagent, which is more reactive with organoboranes.

The reaction of alkyl derivatives of 9-Borabicyclo[3.3.1]nonane (9-BBN) with (1) results in migration of the B-cyclooctyl group, producing N-Boc-5-aminocyclooctanol (eq 7).

1. (a) Genêt, J.-P.; Mallart, S.; Greck, C.; Piveteau, E. TL 1991, 32, 2359. (b) Greck, C.; Bischoff, L.; Hajicek, J.; Genêt, J.-P. BSF(2) 1994, 131, 429.
2. Genêt, J.-P.; Hajicek, J.; Bischoff, L.; Greck, C. TL 1992, 33, 2677.
3. Carpino, L. A.; Giza, C. A.; Carpino, B. A. JACS 1959, 81, 955.

Jean-Pierre Genêt & Christine Greck

Ecole Nationale de Chimie de Paris, France

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