23293-50-7Relevant articles and documents
Lithium Metalloid Exchange: Reactivity Studies of an Allenyllithium Reagent using an Isomeric Pair of Allenyl and Prop-2-ynyl Stannanes
Reich, Hans J.,Mason, J. Derek,Holladay, Jonathan E.
, p. 1481 - 1483 (1993)
The regioselectivity and reactivity of silylation of an allenyl-prop-2-ynyllithium reagent is different when a sequential or in situ Li/Sn exchange is used to prepare it; the evidence points to a solvent-separated ion pair as the transient species trapped during the in situ experiment.
Synthesis of the Verapamil Intermediate through the Quaternary Carbon-Constructing Allylic Substitution
Kobayashi, Yuichi,Saeki, Ryohei,Nanba, Yutaro,Suganuma, Yuta,Morita, Masao,Nishimura, Keita
supporting information, p. 2655 - 2659 (2017/11/28)
In the present study, the key secondary allylic picolinate was synthesized via Pd(PPh 3) 4 -catalyzed coupling of the TBS ether of (R, Z)-4-iodo-5-methylhex-3-en-2-ol with allyl-MgBr. Allylic substitution of the picolinate with the copper reagent derived from 3,4-(MeO) 2 C 6 H 3 MgBr and Cu(acac) 2 in a 2:1 ratio afforded the anti S N 2′ product with complete chirality transfer and 91% regioselectivity. Synthetic manipulation of the olefin moiety led to the nitrile group, generating the intermediate for the synthesis of (S)-verapamil.
Pd(O)-catalyzed addition of Me3SnSnMe3 to α,β-alkynic aldehydes and ketones. Synthesis of (Z)-β-trimethylstannyl α, β-alkenic aldehydes and ketones. Preparation and synthetic uses of substituted (Z)-4-trimethylstannyl-1,3-butadienes
Piers,Tillyer
, p. 2048 - 2063 (2007/10/03)
Treatment (dry tetrahydrofuran, reflux) of the α,β-alkynic aldehydes 26-28 and ketones 29-36 with Me3SnSnMe3 in the presence of a catalytic amount of (Ph3P)4Pd provides fair to excellent yields of the corresponding (Z)-β-trimethylstannyl α,β-alkenic aldehydes 41-43 and ketones 44-51. The carbonyl compounds 41-51, upon reaction with methylenetriphenylphosphorane under suitable conditions, are smoothly converted into the (Z)-4-trimethylstannyl-1,3-butadienes 61-71, respectively. Treatment of the aldehyde 41 with the anion of trimethyl phosphonoacetate and the aldehyde 42 with the anion of the phosphonoacetate 73 produces excellent yields of the 5-trimethylstannyl-2,4-heptadienoates 72 and 74, respectively. The synthetic potential of (Z)-4-trimethylstannyl-1,3-butadienes is illustrated by the conversion of 62 into the functionalized, stereodefined conjugated dienes 76 and 78 and by transformation of 87 into the structurally novel diene 84. Diels-Alder reactions of 84 with tetracyanoethylene and dimethyl acetylenedicarboxylate provide the spiro[3.5]nonane derivatives 88 and 89, respectively.
The origin of regioselectivity in an allenyllithium reagent
Reich, Hans J.,Holladay, Johnathan E.,Mason, J. Derek,Sikorski, William H.
, p. 12137 - 12150 (2007/10/03)
A pair of allenyl (5-methyl-4-(trimethylstannyl)-2,3-hexadiene, 1A-Sn) and propargyl (5-methyl-2-(trimethylstannyl)-3-hexyne, 1P-Sn) stannanes were prepared and used in a series of lithium-tin exchange experiments (both give the same lithium reagent, 1A-L
A Regioselective and Stereospecific Synthesis of Allylsilanes from Secondary Allylic Alcohol Derivatives
Fleming, Ian,Higgins, Dick,Lawrence, Nicholas J.,Thomas, Andrew P.
, p. 3331 - 3350 (2007/10/02)
Primary and secondary allylic acetates and benzoates react with the dimethyl(phenyl)silyl-cuprate reagent to give allylsilanes, provided that the THF in which the cuprate is prepared is diluted with ether before addition of the allylic ester.The reaction is reasonably regioselective in some cases: (i) when the allylic system is more-substituted at one end than the other, as in the reactions 4->5 and 9->10; (ii) when the steric hindrance at one end is neopentyl-like, as in the reactions 15->16; and (iii) when the disubstituted double bond has the Z configuration, as in th e reactions Z-19->E-21 or, better, because the silyl group is becoming attached to the less-sterically hindered end of the allylic system, Z-20->E-22.The regioselectivity is better if a phenyl carbamate is used in place of the ester, and a three-step protocol assembling the mixed cuprate on the leaving group is used, as in the reactions 23->24 and E- or Z-29->E-21, or, best of all, because the silyl group is again becoming attached to the less-sterically hindered end of the allylic system, E- or Z-30->E-22.This sequence works well to move the silyl group onto the more substituted end of an allyl system, but only when the move is from a secondary allylic carbamate to a tertiary allylsilane, as in the reaction 38->39.Allyl(trimethyl)silanes can be made using alkyl- or aryl-cuprates on trimethylsilyl-containing allylic esters and carbamates, as in the reactions 40->41, and 43->44.The reaction of the silyl-cuprate with allylic esters and the three-step sequence with the allylic carbamates are stereochemically complementary, the former being stereospecifically anti and the latter stereospecifically syn.Homochiral allylsilanes can be ma de by these methods with high levels of stereospecificity, as shown by the synthesis of the allylsilanes 54, 58 and 59.
Synthesis of Allenylsilanes from Propargyl Carbamates
Fleming, Ian,Takaki, Ken,Thomas, Andrew P.
, p. 2269 - 2274 (2007/10/02)
Pent-3-yn-2-yl acetate (1) reacts with dimethyl(phenyl)silyl cuprate reagent to give a mixture of allenylsilane and propargylsilane.The corresponding N-phenylcarbamate (4) gives only the allenylsilane.Four other examples of this regioselective reaction are reported.The stereochemistry is largely syn.
