Dipiperidines

Prepa.ra.tion, The preparation of amorphous high (99%) 1,2-polybutadiene was first reported iu 1981 (27). The use of a heterocycHc chelating diamine such as dipiperidine ethane iu the polymerization gave an amorphous elastomeric polymer of 99.9% 1,2 units and a glass-transition temperature of +5°C. In a previous description (53,54) of the use of a chelating diamine such as A/A/N(N -tetramethylethylene diamine, an 80% 1,2-polybutadiene with a glass-transition temperature of —30°C was produced. 

The unique feature about anionic polymerization of diene to produce homopolymer was that the microstructure of the homopolymer could be altered and changed at will to produce unique physical and chemical properties. These microstructural changes can be introduced before, after or during the polymerization. For example, chelating diamines, such as tetramethyl ethylene and diamine (TMEDA) (18), with the alkyl-lithium catalyst have been used to produce polymer with 80 1,2 addition products, while the use of dipiperidine ethane (DPE),with same catalyst has produced polybutadiene with 100 1,2 addition product. 

Dipiperidino-tetrozido-cuprote or Dipiperi-dine-tetrazi do-copper, (C5H12N)2[Cu(N3)4l mw 403.94, N 48.54% solid mp 125°, bp -expl at 200—205° when thrown on the preheated metallic block burns in flame wi th a crackling noise very insensitive to impact (100cm with 1 kg wt). It can be prepd by dissolving Cu azide in dipiperidine (Ref 4)... 

Tributyltin hydride, 97%, crotonaldehyde, 99%, 1,1 -(azodicarbonyl)-dipiperidine, 99%, and lithium aluminum hydride, 95%, were purchased from Aldrich Chemical Company, Inc. Hexane refers to a distilled, isomeric mixture of CgHu. 

Dipiperidine and derivs 5 D1490 dinitrosopiperidines 5 D1490 dipiperidino-diazido-copper 5 D1490 dipiperidino-tetrazido-cuprate 5 D1490... 

In 1968, Mukaiyama et al.70 discovered that magnesium alkoxides—generated by reaction of Grignard reagents with aldehydes—when treated in situ with l,r-(azodicarbonyl)dipiperidine (ADD) (69), suffer oxidation to the corresponding ketones. 

Scheme 10. Proposed mechanistic cycle for Suzuki-Miyaura cross-coupling based on tbe observation of binuclear palladium complexes. L=l.l -(cyclohexylpbospbanediyl)dipiperidine.

Figure 7.10 Structures of the quinolizidine alkaloids, lupinine (21), lupanine (22), cytisine (23) and multiflorine (24) and of a dipiperidine alkaloid of the ammodendrine type (25).

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