CARBANION-ACCELERATED CLAISEN REARRANGEMENTS .8. PHOSPHONAMIDE ANION-STABILIZING GROUPS

被引:59
作者
DENMARK, SE
STADLER, H
DOROW, RL
KIM, JH
机构
[1] Roger Adams Laboratory, Department of Chemistry, University of Illinois, Urbana
关键词
D O I
10.1021/jo00017a016
中图分类号
O62 [有机化学];
学科分类号
070303 ; 081704 ;
摘要
The utility of various phosphonamide groups has been examined in the context of the carbanion-accelerated Claisen rearrangement (CACR). An extensive survey has identified the N,N'-dibenzyl-1,3,2-diazaphospholidine group 11 to be optimal in the ease of construction of the CACR precursors and the facility and stereoselectivity of the rearrangement. Using n-butyllithium as the base, the phosphonamides rearranged readily at -20-degrees-C with complete regioselectivity and in good yield (74-79%). The phosphonates also showed a high level of diastereoselectivity (> 95% de) but the yield from the (Z)-2-butenyl precursor (anti product) was only 45%. A chiral N,N'-dibenzyl-1,3,2-diazaphospholidine 12 derived from trans-1,2-cyclohexanediamine was examined. Although the CACR proceeded very cleanly (71-85%) and with high internal selectivity (94% de), the relative asymmetric induction was poor (16-20% de). This was also the case for a chiral N,N'-dibenzyl-1,3,2-diazaphosphorinane 15 derived from (R,R)-1,3-diphenyl-1,3-propanediamine and N,N'-dibenzyl-1,3,2-diazaphosphepine 16 derived from 6,6'-dimethyl-2,2'-diaminobiphenyl. The characteristic features of the CACR were compared with the aryl sulfone and phosphonate versions.
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页码:5063 / 5079
页数:17
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