Organic Syntheses via Transition-Metal Complexes. 110.¹ A Convenient Regio- and Stereoselective Approach to the Angular Allylation of Bicyclic Cyclopentadienes Generated by the (1-Alkynyl)carbene Complex Route

Abstract

Reaction of the [2-(1-cyclopentenyl)ethynyl]carbene tungsten compound 1a with secondary allylamines RNHsCH 2 CHdCH 2 (R ) CH 2 CHdCH 2 , CH 2 CH 2 CH 3 , PhCH 2 ) (2a-c) and pyridine affords (C6a-allyltetrahydropentalen-1-ylidene)amines 3a-c in 72-77% yields. Compounds 3 result from a highly regio-and stereoselective N,C-allyl rearrangement of 1-(allylamino)cyclopentadiene precursors 7, which are generated in a kinetically controlled process from compound 1a. The reaction has been successfully extended to the formation of (C7a-allylpentahydro-3aH-inden-1-ylidene)amines 8a-c from [2-(1-cyclohexenyl)ethynyl]-carbene tungsten complex 1b and (C8a-allylhexahydro-3aH-azulenylidene)amines 12a,b from [2-(1-cycloheptenyl)ethynyl]carbene tungsten complex 1c.

Six‐Membered Ring Formation from Lewis Acid Promoted Reactions of 2‐Substituted 2‐Alkenyl Amides and Esters of Ethenetricarboxylate

“…N ‐Benzyl‐2‐methylallylamine and N ‐cyclohexyl‐2‐methylallylamine were prepared according to the literature method 19…”

“…The crude allylic bromide thus obtained was then used for the next step without further purification. The literature procedure19 was employed for the amination reaction with benzylamine.…”

“…N ‐Benzyl‐2‐phenyl‐2‐propenylamine was prepared by the reaction of α‐(bromomethyl)styrene21 and benzylamine 19…”

Bicyclic Cyclopentadienes with N,S Substituents

“…by addition of enamines [4] or by addition of a variety of different protic nucleophiles NuH [e.g. RCϭNR(RЈCO)CH 2 , [5] R 2 NH, [6,7] R 2 PH, [8] RC(ϭO)OH and ROH, [8,9] RC(ϭX)SH (X ϭ O, NH, NR) [10] and RSH [11] ]. [6,12] The latter procedure was shown to be well suited for the generation of highly reactive bicyclic cyclopentadienes, such as tetrahydropentalenes [5,6] or tetrahydroindenes, [7,8] and most notable also for the attachment of anionic substituents to the cyclopentadiene ring, which is not achieved by more conventional routes.…”

“…1S*,7R*,10R*,11S*)-Pentacarbonyl{8,10-diethoxy-16-(2-pyridylthio)penta-cyclo[8.5.2.01,11 .02,9 .03,7 ]heptadeca-2,8,16-triene-N}-tungsten (9a): 1-Ethoxy-3-(2-pyridylthio)-4,5,6,7-tetrahydro-3aH-indene (5b) (68 mg, 0.25 mmol) and compound 1a (118 mg, 0.25 mmol) in 2 mL of n-pentane/diethyl ether, 1:1, was stirred at 20°C. Compound 1a was consumed completely (TLC test) after 20 h while a precipitate was formed.…”