Bis allylic bromide

Larger Rings.—Ring-forming Reactions. The Ni(CO)4-induced cyclization of the bis-allylic bromides (73) was the key step in a synthesis of casbene. More large-ring... 

Z,Z-Cyclodeca-l,6-dienes have been prepared from the bis-allylic bromide (240) (Scheme 22) by coupling with dimethyl malonate or the formaldehyde dianion equivalent, TosMIC yields are around 60%, when high-dilution conditions are used. In related work, it has been shown that 2-(malonic esters can be cyclized intramolecularly in moderate yield using EtOK and 18-crown-6 in very dilute DMSO solutions. ... 

It should be noted here that the lithium salt of hexamethyldisilazane li-HMDS 492 (and Na-HMDS-(486) and K-HMDS in Sections 5.1.2 and 5.1.3), which is readily obtained on treatment of a solution of HMDS 2 in hexane or THF with butyUithium at -78 °C, is not only a very useful and selective strong base, e.g. for Wittig reactions, but can also add to carbonyl groups to yield the silylated Schiff bases or nitriles (cf. Sections 4.7 and 5.1.3) or to nitriles to afford N-silylated ami-dines. Alkylation of the Li-HMDS 492, e.g. with allyl bromide, affords, furthermore, N,N-bis(trimethylsilylated) primary amines such as 43 [64]. The combina-... 

In 1975, van der Baan and Bickelhaupt reported the synthesis of imide 37 from pyridone 34 as an approach to the hetisine alkaloids, using an intramolecular alkylation as the key step (Scheme 1.3) [23]. Beginning with pyridone 34, alkylation with sodium hydride/allyl bromide followed by a thermal [3,3] Claisen rearrangement gave alkene 35. Next, formation of the bromohydrin with A -bi omosuccinimide and subsequent protection of the resulting alcohol as the tetrahydropyranyl (THP) ether produced bromide 36, which was then cyclized in an intramolecular fashion to give tricylic 37. 

The addition of a large excess of bis(cj-alkenyl)zinc compounds to the TiC -catalyzed polymerization of propene resulted in an increased polymer yield, but a reduction in the molecular weights of the polymers.64 This suggests that the diorganozinc compounds are both co-catalysts and chain-transfer agents in this polymerization. The catalyst activity decreased in the order bis(3-butenyl)zinc < bis(7-octenyl)zinc < chlorodiethylaluminum. Bis(7-octenyl)zinc was co-polymerized with propene to afford hexylzinc side chains, whose zinc-carbon moieties were converted to vinyl groups by the addition of allyl bromide. 

The bismuth- or tantalum-promoted allylation of aldimines 187 (R1 = Ph or PhCH=CHCH2 R2 = Me, Ph or PhCH2) with allyl bromide in the systems Bi/Bu4N+ Br /MeCN or Ta/Bu4N+ Br /MeCN yields the amines 188193. 

Allyl bromide and bis(trlbutyltin) oxide were obtained from Aldrich Chemical Company, Inc. 

Allylation of aldehydes.1 Metallic Bi (1.2 equiv.) effects reaction of allyl bromides or iodides with aldehydes to form homoallylic alcohols in 70-98% yield. Example ... 

Unsubstituted ODC are alkylated to 1,19-dialkyl-ODC with alkyl iodide or allyl bromide, while 1-ethoxycarbonyl- and l,19-bis(ethoxycarbonyl)-ODC are decarboxylated to 19-unsubstituted ODC and corrole respectively by alcoholic alkali. 19-Acyl and -carboxyl groups are also eliminated by alcoholic alkali (2 N KOH, EtOH, 60 °C) and NEt3-AcOH respectively. 2... 

Scheme 4.2 General synthetic scheme for cinchona-derived dimeric quaternary ammonium salts, (a) bis(Bromomethyl)-linkers (0.5 equiv.), EtOH-DMF-CHCI3 (5 6 2), r.t. or reflux, (b) Allyl bromide or benzyl bromide (6.0 equiv.), 50% KOH (10.0 equiv.), CH2CI2, r.t.

Furthermore, it has recently been demonstrated (14) that the pentaco-ordinate 7r-allyl complex similar to (IV) reacts with allyl bromide in methanol to form bis(allyl) and methyl 3-butenoate. This is consistent... 

By using (chiral source, high enantioselectivity (up to 92% ee) has been attained in an aqueous medium H20-EtOH (1 1) (Scheme 46).191 Changing to other mixed solvents leads to lower selectivities (72% ee in H20-MeCN (1 1), 76% ee H20-THF (1 1), and 66% ee in H20-EtOH (1 9)). The reaction of allyl iodide in place of allyl bromide decreases the selectivity from 92% to 76% ee. 

The allylation of imines with allylindium reagents in organic solvents gives the corresponding homoallylic amines.251-253 Under solvent-free conditions, the indium-mediated reaction of iV-benzylideneaniline furnishes a mixture of mono-allylated 79 and bis-allylated products 80 (Equation (56)). The bis-allylated product 80 presumably arises via a formation of an iminium salt, which is subsequently attacked by the allylindium nucleophiles. Formation of 80 is entirely suppressed by addition of allyl bromide to indium metal prior to any addition of the imine (Grignard-type reaction).254... 

Polymerization was carried out in benzene in the presence of bis-(7r-allylnickel halides). The latter were prepared from nickel carbonyl and allyl halide (allyl bromide, crotyl chloride, bromide, or iodide etc.). The results of the polymerization runs are reported in Table I. The data indicate that all of the bis(7r-allylnickel halides) initiate by themselves the stereospecific butadiene polymerization yielding a polymer with 97-98% 1,4-units. The cis-l,4/trans-l,4 ratio depends on the halide in the dimeric r-allylnickel halide but not on the nature of allylic ligand. The case of bis(7r-crotylnickel halides) shows the effect of halide on microstructure, for whereas (C4H7NiCl)2 initiates cis- 1,4-polybutadiene formation, trans-1,4 polymers are produced by (C4H7NiI)2. The reactivity increase in the series Cl < Br < I. 

---