[91166-50-6]  · C10H28N2Si2  · 1,4-Bis(dimethylamino)-1,1,4,4-tetramethyldisilethylene  · (MW 232.52)

(reagent for the protection of primary amines with lower pKa values, such as substituted anilines, as their tetramethyldisilylazacyclopentane or Stabase adduct; precursor of tetramethyldisilylthiacyclopentane, a sulfur transfer reagent)

Physical Data: bp 100-103 °C/13 mmHg; d 0.824 g cm-3.

Preparative Method: the reagent is prepared as a colorless liquid in 90% yield by treating commercially available bis(chlorodimethylsilyl)ethane with 5 equiv of dimethylamine in ether at 0 °C for 5 h.

Handling, Storage, and Precautions: the liquid vapors are heavier than air and may travel a considerable distance to a source of ignition. Vapor-air mixtures are explosive above the flash point of 14 °C. Use in a fume hood.

Protection of Primary Aromatic Amines.1

The title reagent is used for the preparation of Stabase derivatives of primary amines, and is particularly useful for the protection of primary aromatic amines with pKa values of 10-11 (see 1,2-Bis(chlorodimethylsilyl)ethane). The protection of substituted anilines is achieved by heating equimolar amounts of the title compound and the anilines in the presence of Zinc Iodide (0.5 mol %) under a slow stream of nitrogen at 140 °C for 5 h. In many cases the products can be purified by vacuum distillation. Cleavage of the Stabase adducts to the corresponding primary amines can be performed in ether in the presence of 2 equiv of methanol and a small amount of p-toluenesulfonic acid monohydrate (0.2 mol %). The tetramethyldisilylazacyclopentane or Stabase adduct (3) is a particularly attractive protecting group due to its ease of preparation, base stability, and facile removal (eq 1).

The title compound was utilized to protect 2-amino-6-bromopyridine (4) in 72% yield in a sequence to prepare helicopodant (7) (eq 2).2

Sulfur Transfer Reagent.

The reagent was used to prepare 2,2,5,5-tetramethyl-2,5-disila-1-thiacyclopentane (8) which acts as a sulfur transfer reagent. An example of this reaction is shown in eq 3.3

1. Guggenheim, T. L. TL 1984, 25, 1253.
2. Deshayes, K.; Byoene, R. D.; Chad, I.; Knobler, C. B.; Diederich, F. JOC 1991, 56, 6787.
3. Guggenheim, T. L. TL 1987, 28, 6139.

Fatima Z. Basha & Anwer Basha

Abbott Laboratories, Abbott Park, IL, USA

Copyright 1995-2000 by John Wiley & Sons, Ltd. All rights reserved.