New, Efficient Method for the Synthesis of Allyltitanium Compounds from Allyl Halides or Allyl Alcohol Derivatives via Oxidative Addition. A Highly Efficient and Practical Synthesis of Homoallyl Alcohols

Bis alkoxytitanacyclopropanes and -propenes (Kulinkovich reagents): Versatile reagents for carbon—carbon bond formation

“…This problem was solved independently by Sato and Cha [5,6]. Both found that the primarilly formed Kulinkovich reagent -the titanacylcopropane 13 -can undergo ligand exchange with other monosubstituted alkenes to give substituted titanacyclopropanes (e.g.…”

“…Intramolecular coupling of diynes (40) is possible and provides [5,5]-, and [5,6]-bicyclic cyclopentadienols 41 (equation 13).…”

Mechanism of the Kulinkovich Cyclopropanol Synthesis: Transfer‐Epititanation of the Alkene in Generating the Key Titanacyclopropane Intermediate

“…The course of the Kulinkovich reaction, when an ethyl Grignard reagent is employed, has been depicted as proceeding via diethyltitanium() diisopropoxide (7) to give the titanacyclopropane 9, without specifying whether titanium() diisopropoxide (8) is ever set free before it recombines to form 9 (path b), or whether 9 forms directly from 7 with the elimination of ethane (path a) (Scheme 1). The interaction of 9 with an ester to form the cyclopropanolate salt precursor to 4, is viewed as occurring by the generally accepted reaction pathway for vicinal dimetalloethane reagents.…”

“…In modifications of the Kulinkovich procedure, where the Grignard reagent [7] (or an analogous organolithium reagent [11] ) does not serve as the source of the olefin or acetylene but only as a reductant for the Ti(OiPr) 4 , it has been assumed without proof that the dialkyltitanium() dialkoxide formed decomposes analogously to that mentioned above, namely 10 to 11 as does 7 to 9, but then the added allylic halide, olefin or acetylene undergoes ligand exchange with the intermediate titanacyclopropane 11 to form the derived titanium reagents 12, 13 or 14 (Scheme 2). Scheme 2 This viewpoint is exemplified by the work of both the Sato group [7] and the Cha group.…”

First Titanium‐Catalyzed 1,4‐Hydrophosphination of 1,3‐Dienes

“…The reaction was then performed with [Ti- 4 ]. [19] Surprisingly, the reaction under these conditions completely lost its regioselectivity leading to a mixture of 1,2-and 1,4-tail-addition products (1 a and 2 a) accompanied by the two 1,4-head-addition products ((Z)-and (E)-2-methylbut-2-enyl)diphenylphosphine). We next envisaged the use of a phosphine-substituted titanocene as it is evident that the presence of the trimethylphosphine is a determining element for the regioselectivity of the reaction.…”