B. Randrianoelina

Organometalliques (M = Mg, Zn, Al) derivant de bromures α-alleniques: I. Preparation des organometalliques et etude de leur reactivite vis a vis des derives halogenes

Abstract The preparation of organo-magnesium, -zinc and -aluminum compounds from several primary α-allenic bromides, and their structures, stabilities and reactivities towards various halides are described. The organomagnesium compounds react readily with halides in the presence of Li2CuCl4.

Synthese d'heterocycles oxygenes a groupe vinylidene exocyclique par voie organosilicique - partie II: Preparation de vinylidene-5 dioxannes-1,3

Abstract The α-silyloxypropargyltrimethylsilanes regiospecifically react with aliphatic aldehydes to lead to alkyl-substituted 5-vinylidene-1,3-dioxanes, in a one-pot reaction.

Action du trimethylsilyl-1 butyne-2 sur les derives carbonyles en presence de catalyseurs: synthese d'alcools α-alleniques ou de derives chloropreniques.

Resume 1-trimethylsilyl 2-butyne reacts with carbonyl compounds in the presence of titanium tetrachloride or tetra-n-butylammonium fluoride, to produce mainly α-allenic alcohols; with titanium tetrachloride, it is also possible to obtain chloroprenic derivatives only.

Reactivite de silanes propargyliques α-fonctionnels vis a vis des derives carbonyles : preparation d'alcools-ethers, de diols et de dioxannes alleniques.

Abstract Type 1 functional propargyltrimethylsilanes react with carbonyl derivatives, in the presence of titanium tetrachloride or tetra-n-butylammonium fluoride, to produce allenic alcohols-ethers, diols and dioxanes.

Synthèse régiosélective d'amines α-alléniques par aminométhylation-désilylation de propargyltriméthylsilanes

Abstract A very convenient method to prepare α-allenic amines from propargyltrimethyl-silanes and secondary amines via an aminomethylation-desilylation process is described.

Organometalliques (M = Mg, Zn, Al) derivant de bromures α-alleniques: II. Reactivite vis a vis des derives carbonyles

Abstract Organomagnesium compounds prepared from α-allenic bromides react readily with aliphatic and aromatic aldehydes and ketones to give in most cases a mixture of a β-allenic and a dienic alcohol. They react with aldimines which leads to a dienic secundary amine. The corresponding organozinc compounds react readily with aldehydes, while yields are low with ketones; in all cases, only the β-allenic alcohols are formed. The reaction of the corresponding organoaluminium compounds with aldehydes, ketones and ketals give β-allenic products in good yields.

Synthèse et protodésilylation de silanes α-alléniques hétérocycliques

Abstract Some ω-functional propargylic-bis-trimethylsilanes, easily prepared from propargyltrimethylsilane through classical methods, allow a convenient one-pot synthesis of 2-alkyl-4-trimethylsilyl-3-vinylidenetetrahydropyranes and N-alkyl-4-trimethylsilyl-3-vinylidene-piperidines. These new silanes undergo a protodesilylation reaction leading to conjugated heterocyclic dienes.