Beta-silylated homopropargylic amines via the asymmetric allenylboration of aldimines.
The asymmetric synthesis of alpha-trimethylsilylpropargylic carbamines (7) through the addition of allenylboranes 4 to N-H aldimines is reported. The insertion of TMSCHN2 into enantiomerically pure B-alkynyl-10-TMS-9-borabicyclo[3.3.2]decanes 3 followed by a sterically driven 1,3-suprafacial borotropic shift proceeds with complete stereospecificity to produce 4 in diastereomerically and enantiomerically pure form. These reagents give 7 (51-85%, syn/anti >99%, 92-9% ee) permitting the recovery of 8 (53-63%). Allenylboranes 4 also provide a convenient route to optically pure allenylsilanes 13 (55-94%) through their protonolysis. [reaction: see text]
Gonzalez
Ana Z
AZ
Department of Chemistry, University of Puerto Rico, Rio Piedras, Puerto Rico 00931-3346, USA.
Soderquist
John A
JA
D000466:Alkadienes / Q000737:chemistry*; D000473:Alkanes / Q000737:chemistry; D000480:Alkynes / Q000737:chemistry; D001880:Boranes / Q000737:chemistry*; D001643:Bridged Bicyclo Compounds / Q000737:chemistry; D007097:Imines / Q000737:chemistry*; D009942:Organometallic Compounds / Q000138:chemical synthesis*; D010293:Pargyline / Q000031:analogs & derivatives* / Q000138:chemical synthesis*; D011522:Protons; D013237:Stereoisomerism; D014297:Trimethylsilyl Compounds / Q000737:chemistry*
D000466:Alkadienes; D000473:Alkanes; D000480:Alkynes; D001880:Boranes; D001643:Bridged Bicyclo Compounds; D007097:Imines; D009942:Organometallic Compounds; D011522:Protons; D014297:Trimethylsilyl Compounds; C025947:propadiene; D010293:Pargyline; C012867:decane