ライフサイエンスコーパス: bridgehead

1 tes that are held together by two orthoester bridgeheads.

2 substitution at a methylene attached to the bridgehead (1-) position of the 2-azabicyclo[2.1.1]hexan

3 )N) bridgehead with an ethano (NCH(2)CH(2)N) bridgehead affects the conformational equilibrium of the

4 ating evidence for the structures of certain bridgehead alkene natural products while leading to the

5 nantholactams were formed by stereoselective bridgehead alkene reduction, a process that transfers st

6 ic system of the taxane family, containing a bridgehead alkene, is forged via a vicinal difunctionali

7 e addition of phenylchlorocarbene (PhCCl) to bridgehead alkenes adamantene and homoadamantene, respec

8 The exclusive product in each case was the bridgehead alkyl chloride formed by fragmentation of the

9 nforces C(3) symmetry at the sila-diamondoid bridgeheads, allowing each electrode to couple into the

10 he steric effects of the substituents at the bridgehead allows for the precise control of the directi

11 transannular cyclization and reduction of a bridgehead alpha-chloro amine functionality produces the

12 ates are multiply functionalized and carry a bridgehead alpha-ketol array which was key to isomerizat

13 The ring size, bridgehead amino acid chirality, and side-chain amide bo

14 nvolves cleavage of the C-C bond between the bridgehead and one carbonyl atom, C(bridge)-C(O), yieldi

15 ovalent exchange reactions at the orthoester bridgeheads, and as a hydrogen bond donor it acts as a s

16 Two new classes of agonists in which the bridgehead anilino group from our first series was repla

17 oming a significant drawback of our original bridgehead anilino-substituted series.

18 contain a trisubstituted vinyl group at the bridgehead, as showcased in several stereospecific trans

19 conserved lysine and cysteine residues, the bridgehead atom of the dithiolate ligand, or the reduced

20 ion, we have studied the effect of different bridgehead atoms of the [2.2.1]bicyclic system and the p

21 direct control of the stereochemistry of the bridgehead atoms of the fused ring using new MDOs self-a

22 he substitution of positions adjacent to the bridgeheads atoms which would otherwise be vulnerable to

23 capabilities of two 10-pai electron nitrogen bridgehead bicyclic [5,6]-fused ring systems, imidazo[1,

24 The modularity afforded by the pendant bridgehead boron pinacol esters generated during the cyc

25 The versatility of the bridgehead boronic ester was demonstrated in several fun

26 ion is highly selective for the formation of bridgehead boronic esters and is compatible with a broad

27 The larger slope is due to the smaller bridgehead-bridgehead distance in the bicyclopentane rin

28 The fragmentation reaction for bridgehead-bromine-substituted derivatives was much fast

29 The installation of bridgehead bulk in the -SCH2CR2CH2S- dithiolate (R = Me,

30 mbined in a thermodynamic cycle to provide a bridgehead C-H bond dissociation energy (BDE) of 109.7 +

31 Bridgehead C-H bond dissociation enthalpies of 105.7 +/-

32 These selective transformations of both BCP bridgehead (C(3)) and bridge (C(2)) positions enable acc

33 elective activation and functionalization of bridgehead (C(3))-boronic pinacol esters (Bpin), leaving

34 rearrangements were employed in building the bridgehead (C20) and the spiroanilide (C7) quaternary ce

35 order of increasing strain in the resulting bridgehead carbocation, but the range of rate constants

36 eneration of a new stereogenic center on the bridgehead carbon (C8a).

37 aring a pendant hydrazino functionality on a bridgehead carbon atom can be obtained in high yield (68

38 cene, such that the bulky methyl-substituted bridgehead carbon atoms are attached to C2 and C3 of the

39 ptor are attached via alkyne linkages to the bridgehead carbon atoms of bicyclo[2.2.2]octane and all

40 bridged, have methyl groups adjacent to the bridgehead carbon atoms, and have aryl substituents prot

41 , and proximity of the forming olefin to the bridgehead carbon of the bicyclic affect the efficiency

42 Epimerization of the 7'a bridgehead carbon under acidic conditions was observed f

43 bridges along with one chiral center at the bridgehead carbon.

44 ubstituent rather than a methyl group at the bridgehead carbon.

45 y from the bridgehead lactam nitrogen to the bridgehead carbon.

46 The geometry of the bridgehead carbons made S(N)2 reactions impossible.

47 he trans-dimethyl geometry of the quaternary bridgehead carbons via a reductive cyclization.

48 carrying various functionality at one of the bridgehead carbons, have been accomplished.

49 ylative allylation to install the quaternary bridgehead center.

50 tion of synthetic utility, a series of novel bridgehead CF(3)-substituted isoquinuclidines was prepar

51 The results also show that a change in the bridgehead chirality of the 5.6.5 scaffold brings about

52 analogues with different bridge lengths and bridgehead chirality.

53 (1,1'-5) bridge length (21 and 22 atoms) and bridgehead configuration, we may hypothesize that they a

54 esis of compounds similar to 2, containing a bridgehead cyclopropane, and compounds of type 3 with an

55 first bridgehead sultams and the only known bridgehead disulfonimide are described.

56 s if the second step requires formation of a bridgehead double bond.

57 11 membered bicyclic ring consisting of two bridgehead double bonds (anti-Bredt) within a triterpene

58 ss five rearranged fusicoccanes with unusual bridgehead double bonds.

59 nes, compounds having exceptionally strained bridgehead double bonds.

60 the Mediterranean appears consistent with a bridgehead effect resulting from the postglacial expansi

61 ation reactions, including the generation of bridgehead enolates, thus enabling the total synthesis o

62 e congested central cycloheptene ring at the bridgehead enone site; the required cyclization precurso

63 for assembly of the ethyl side chain at C6, bridgehead epimerization at C5, installation of the C2-t

64 Additionally, we found evidence of one bridgehead event: a likely Eastern US source for the cen

65 ed QS pathway intermediates that represent a bridgehead for adjuvant bioengineering.

66 ent enzyme database dictionaries and provide bridgeheads for the annotation of unexplored sequence sp

67 or quantification of the deformations of the bridgehead functionalities and provided a strategy for t

68 ptycenes bearing H (1-H) or Bu (1-Bu) at the bridgeheads gave triptycenes with triphenylene blades.

69 We find that bridgehead Ge centers can be selectively functionalized

70 nt geometry with two phosphorus atoms at the bridgehead has been synthesized.

71 was discovered, which represents 14-membered bridgehead heterocycles, pyrrolyl-diazabicyclo[8.3.1]tet

72 photoswitches, heteroaryl azobenzenes with N-bridgehead heterocycles-pyrazolo[1,5-a]pyrimidine and 1,

73 product, the propargylic substituent and the bridgehead hydrogen are cis with respect to each other o

74 n the allylic hydroxyl group is trans to the bridgehead hydrogen are found to be the electrostatic in

75 The loss of the bridgehead hydrogen from the (3S,5S)-carbapenam during t

76 nal modifications to 14 also showed that the bridgehead hydroxyl group could be replaced with a propi

77 The tandem reaction proceeds through a bridgehead iminium ion, a functionality that has rarely

78 is further suggested that the nature of the bridgehead in the dithiolate ligand can exert a stereoel

79 yclic systems with a nitrogen 10 atom at the bridgehead, including indolizidines and quinolizidines,

80 bond formation at a prochiral attached-ring bridgehead is reported.

81 cess that transfers stereochemistry from the bridgehead lactam nitrogen to the bridgehead carbon.

82 But the amide groups of bicyclic bridgehead lactams are highly twisted, and this distorti

83 nds (with bond angle 94 degrees ) and the C2 bridgehead leading to anti-endo elimination of the C1-me

84 ons between the incoming heteroarene and the bridgehead methyl group govern the unexpected facial sel

85 g to substituted tetracyclic and pentacyclic bridgehead N-heterocycles, wherein iodonium ylide acts a

86 ting the isolabilities of oxygen-substituted bridgehead natural products based on calculations of ole

87 ee of strain-induced pyramidalization at the bridgehead nitrogen and twist about the amide bond, but

88 Fused heterocyclic systems containing a bridgehead nitrogen atom have emerged as imperative phar

89 ltams (i.e., bridged bicyclic sultams with a bridgehead nitrogen atom) were outlined, and a number of

90 nd azino- and azolo-fused pyrimidones with a bridgehead nitrogen atom.

91 Tricyclic systems with quaternary bridgehead nitrogen atoms are rare but an interesting cl

92 Since substitution at bridge and bridgehead nitrogen atoms can be easily introduced, 1,4,

93 o bicyclic heterocyclic scaffolds containing bridgehead nitrogen centers.

94 is investigated, and a dominant role of the bridgehead nitrogen in reducing the amount of partially

95 n, we show that ammonia is the source of the bridgehead nitrogen of DTMA.

96 t time various heteroaromatic compounds with bridgehead nitrogen, including indolizines, bispyrrolopy

97 bonded network involving the bridge and both bridgehead nitrogens, producing a difference of more tha

98 ate this facile transformation, in which the bridgehead nitrones were isolated in high yields.

99 Unique bridgehead nitrones, 8-oxa-6-azabicyclo[3.2.1]oct-6-ene

100 the recognition face of 5-aza-7-deazaguanine bridgehead nucleosides with respect to purine nucleoside

101 ci was shown to incorporate one label at the bridgehead of (3S,5S)-carbapenam carboxylic acid, but no

102 n of structural distortions of the nonplanar bridgehead olefin and lactam functionalities in 1,2-diaz

103 The reactivity of the strained, bridgehead olefin of this secondary metabolite with biol

104 ngs show how an intermediary, highly diverse bridgehead population gave rise to an invasive, largely

105 Twisted amides containing nitrogen at the bridgehead position are attractive practical prototypes

106 incorporation of diverse substituents at the bridgehead position of diquinanes.

107 In addition, an amino group at the fourth bridgehead position provides a flexible linker for attac

108 bearing a trifluoromethyl substituent at the bridgehead position were obtained with diastereoselectiv

109 on quadricyclane lability, substitution at a bridgehead position with a methyl group produced a quadr

110 ition of the nitrogen of 4-quinolones to the bridgehead position.

111 a high-lying B(sp(3))-B(sp(3)) o-bond at the bridgehead position.

112 ent in the formation of an sp(2) carbon at a bridgehead position.

113 eta, H11alpha (1S,11R) configurations at the bridgehead positions of 22 were established by means of

114 While functionalisation of the tertiary bridgehead positions of BCP derivatives is well-document

115 -OTf group, generating a stable carbocation bridgehead primed for a novel Favorskii-like seven-to-si

116 An unconventional bridgehead propargylation set the key quaternary stereoc

117 er coupling is observed to the unique B-CH-B bridgehead proton (a((1)H) = 7.2 +/- 0.2 G) and to eight

118 stituted-6-azabicyclo[3.2.1]octanes with two bridgehead quarternary carbon centers is reported.

119 ed different handles to be introduced at the bridgehead quarternary center.

120 g the same peripheral substituents but other bridgehead residues failed.

121 H(1-29)-NH2, where Xaa and Yaa represent the bridgehead residues of a side-chain cystine or [i-(i + 4

122 nters can be selectively functionalized over bridgehead Si centers in SiGe adamantanes; we use this c

123 mical shifts, and charge distribution in the bridgehead silylium ions are discussed and compared.

124 hydronium and hydroxide ions at 3-coordinate bridgehead sites.

125 ations, such as fluorine substitution at the bridgehead sp(3) carbon or incorporation of an oxygen at

126 This includes examples containing a bridgehead sp(3) quaternary carbon center as well as the

127 Optimization of the bridgehead substituent led to propionic acid 29 (BG9928)

128 arbon atom and demonstrates the influence of bridgehead substituents and bridging rings on planarity.

129 with results calculated with neglect of the bridgehead substituents for all of the chemical shifts b

130 ch the angle between the exit vectors of the bridgehead substituents is identical to that of a para-s

131 CHeps), which are hydrocarbons for which the bridgehead substituents map precisely onto the geometry

132 hetic studies have featured the synthesis of bridgehead-substituted (C1, C3) BCPs from [1.1.1]propell

133 sequent relay to the remote C3 position by a bridgehead-substituted norbornene mediator.

134 eaking of bonds was studied by investigating bridgehead substitution in 1,3-di-tert-butylbicyclo[1.1.

135 Bridgehead substitution leads to a lengthening of the ce

136 A convergent strategy has allowed access to bridgehead sultam 9 and the related carboxamides 10 and

137 for accomplishing the ring contraction of a bridgehead sultam.

138 Syntheses of the first bridgehead sultams and the only known bridgehead disulfo

139 es by an iridium-catalysed borylation of the bridgehead tertiary C-H bond.

140 The 1,3-adamantanediyl dication 1b with two bridgehead tertiary carbocationic centers was found to b

141 With a NCH(2)CH(2)N bridgehead, the phenyl and the cyclohexyl esters prefer

142 e out conformation, whereas with the NCH(2)N bridgehead, they were found to prefer the folded conform

143 ngth of alkyl substituents at the triptycene bridgeheads to the reaction have been performed, reveali

144 which the Bu groups fill the voids near the bridgehead, was crystalline.

145 al along with the substituent at position-1 (bridgehead) which force attack of the lithium reagent fr

146 Replacing the methano (NCH(2)N) bridgehead with an ethano (NCH(2)CH(2)N) bridgehead affe