Chiral Aminated α‐Methylenebenzocycloalkenes from o‐Bromoaryl Aldehydes and Ketones

Abstract

Chiral tert‐butylsulfinyl imines 3, which are easily prepared from the corresponding bromo carbonyl compounds 1 and tert‐butanesulfinamide (2), undergo a diastereoselective allylation by using indium metal and allyl bromide to give the corresponding homoallyl sulfinylamines 4. Treatment of compounds 4 with a catalytic amount of palladium acetate and triphenylphosphane gives exo‐methylene‐substitutedsulfinylamino)benzocycloalkenes 5 (five‐ to seven‐membered rings) that are easily deprotected with hydrochloric acid to give chiral primary amines 6.

Diastereoselective Indium‐Promoted Allylation of Chiral N‐Sulfinyl Imines

“…A combination of an indium‐promoted allylation of the N ‐sulfinyl aldimine or ketimine 56 (to yield compound 57 ) and an intramolecular cyclization under Heck‐type conditions provided the enantioenriched aminated α‐methylene benzocycloalkane 58 , which started from o ‐bromoaryl carbonyl compound 55 (Scheme ) 20…”

Synthesis of 1‐Aminoindenes through Aza‐Prins‐Type Cyclization

“…Further studies revealed that the reaction of 1 by using a chiral N ‐triflyl phosphoramide ( S )‐ 9 as catalyst and 2‐isopropyl‐4‐methoxyaniline ( 10 ) gave the corresponding 1‐aminoindene derivatives 3 with good enantioselectivities (Scheme ) . The absolute stereochemistry of the obtained 1‐aminoindene derivative was determined by oxidative removal of 2‐isopropyl‐4‐methoxyphenyl group and conversion to the known compound …”

“…With methallyl and 2-phenylallyl-substituted benzaldehydes 6,t he desired sixmembered ring formation proceeded to give 1-amino-1,2-dihydronaphthalene derivatives 7a and b,r espectively. [12] In summary,w ehave developeda na cid-catalyzed aza-Prinstype endo cyclization of 2-alkenylbenzaldehydes with BocNH 2 or aniline derivatives through in situ generation of iminium intermediates. This observation opened the possibility of catalytic asymmetric aza-Prins-type cyclization.…”

“…[11] The absolute stereochemistry of the obtained 1-aminoindene deriv-ative was determined by oxidativer emoval of 2-isopropyl-4methoxyphenyl group and conversion to the known compound. [12] In summary,w ehave developeda na cid-catalyzed aza-Prinstype endo cyclization of 2-alkenylbenzaldehydes with BocNH 2 or aniline derivatives through in situ generation of iminium intermediates. The first catalytic asymmetric variant has also been accomplished by using ac hiral N-triflyl phosphoramide as catalyst.…”

Chiral N‐tert‐Butylsulfinyl Imines: New Discoveries

“…When the starting imines 16 contains a bromine atom at the ortho ‐position, the allylation under standard conditions yielded the corresponding products 218 (Scheme 97). [130] Compounds 218 underwent cyclization under Pd‐catalysis, to give the expected methylenic bicycles 219 .…”