78872-22-7

Upstream product

• 3355-29-1 1,1-dimethyl-3-phenylprop-2-ynyl chloride 
• 542-92-7 cyclopenta-1,3-diene 

Downstream Products

• 75111-16-9 (3,3-Dimethylbicyclo<2.2.1>hept-5-en-exo-2-yl)phenylmethanon 
• 75111-16-9 (3,3-Dimethylbicyclo<2.2.1>hept-5-en-endo-2-yl)phenylmethanon 
• 75111-16-9 (3,3-Dimethyl-bicyclo[2.2.1]hept-5-en-2-yl)-phenyl-methanone 

Relevant academic research and scientific papers

-Cycloaddition of a Stabilised Vinyl Cation with Cyclopentadiene; X-Ray Crystal Structure of the 2:1 Addition Product

Lewis acid-catalysed reaction of 1,1-dimethyl-3-phenylprop-2-ynyl chloride with cyclopentadiene yields a 2:1 addition product via -cycloaddition of an intermediate allenyl cation.

Cycloaddition Reactions of Allenyl Cations with Cyclopentadiene

Propargyl halides R1-C=-C-CR2R3X (14) and cyclopentadiene react with zinc halide catalysis in ether/dichloromethane solution to give 3-halogenobicycloocta-2,6-dienes 13 (R1 = alkyl) or 5-(α-halogenobenzylidene)norbornenes 15 (R1 = aryl).The reactions are interpreted by stepwise - and -cycloadditions of intermediate allenyl cations 1, proceeding via propargylcyclopentenyl cations 5 and bicyclic vinyl cations 9 or 12.If the reactions are initiated by equimolar amounts of silver trifluoroacetate, quenching products of all postulated intermediates are isolated.The relative energies of the intermediate carbenium ions are estimated on the basis of force field calculations and of gas phase stabilities of simple carbocations.Stereochemical studies indicate that the addition reactions proceed via the compact transition state 42 rather than 41.The zinc chloride catalysed reaction of propargyl chloride 14e with cyclopentadiene yields the 2:1 product 17 (structurally assigned by X ray analysis) in addition to the 1:1 product 15e.The formation of 17 is rationalised by a -cycloaddition of allenyl cation 1 with cyclopentadiene.

ADDITION AND CYCLOADDITION REACTIONS OF ALLENYL CATIONS WITH VARIOUS CYCLOALKA-1,3-DIENES

Allenyl cations R-C=C=C(CH3)2(1+), generated in situ from propargyl chlorides and zinc chloride give monocyclic adducts or and cycloaddition products with various cycloalka-1,3-dienes.The mode of addition depends on R and the ring size of the